If Kid A had come unlabelled in an inconspicuous brown paper parcel, arriving at a verdict would have been relatively simple - that it is an intriguing, imaginative and exploratory album which sounds a lot like Radiohead in places. It's resolutely experimental with the odd failure that comes hand in hand with that approach; a bold if elliptical statement that steers away from the mainstream but is an accessible slice of avant pop nonetheless. It took a lot of personal debriefing to come up with the above as the record carries more baggage than a mule train. Playing similar mind games, John Peel has been giving the album airplay claiming - by way of justifying a deviation from his usual playlist criteria - that if he had received the same music on a demo by an unknown group, he would have been very interested anyway.

One thing that gets in the way of objective critical judgement is that concurrent with their massive popularity, the group have often been lauded as 'rock saviours'. Young, white, middle class record buyers have yearned for these saviour figures since the birth of Indie in the late 70s: a group or singer with credibility who can give them a rock version of an out-of-body experience, to get them out of themselves (and therefore out of their everyday situation) and up and away, albeit briefly. This perennial, deep-rooted, almost archetypal need creates a vacuum that those at the head of the queue for the next big thing are likely to balloon up into. The roll call has included groups like Echo And The Bunnymen, U2, The Smiths, The Stone Roses, The Verve, even Simple Minds circa New Gold Dream. They have all produced big, yearning music and also been transcendental after a fashion. And some, like Radiohead, have worn their wounded sensitivity like a badge; but that's OK as it's perfectly in character for the saviour to be a sufferer as well.

To read Thom Yorke whinging about the rigours of stardom, one is tempted to advise him, if he were willing to listen, to shut the fuck up and do something useful. There are few things more tedious than having to listen to rock stars moaning about fame. But he has a point. They are rock product and the conveyor belt they were riding on wasn't going to stop for them, so they had to consciously hop off.

U2 are now tipped, according to Q, to "save rock" in a second coming. It seems they've left behind the archness that punctuated their 97 album, Pop (Gosh, how ironic!), rolled up their sleeves and got back into chest-beating rock'n'roll mode. In 2000, rock music is in as healthy a state as it's ever been and certainly doesn't need saving, except, perhaps, from U2. Radiohead realised that a life of U2-style stadium bluster and big bucks lay ahead of them for the taking if they wanted. Maybe it still does, as they can arguably do it better than anyone else. But not only are they reluctant to acknowledge the deification bestowed upon them, they have, with Kid A, torn up the plans that got them into that position. But have they gone against expectations for the sake of sheer perversity or is this new tack a successful development?

Kid A is no OK Computer Part 2 and the results vindicate their big rethink. And good on them for doing so - it would have been far easier to acquiesce to the pressure, but there is proof here of an active intelligence at work. Some eye-witness reports of their recent London shows have indicated that Yorke seems chary about communicating with his audience, even appearing contemptuous of the people who have put him in the position he now feels he has to rail against. But this album is far from a big "fuck you" to the fans. From the anti-star publicity shots that accompany the album's release to the booklet of non sequiturs hidden in the jewel case underneath the CD itself, Yorke's chosen mode of expression - and at times this is close to a solo album - eschews the public display of running his angst up the flagpole. He has retreated into a sort of cryptic introspection, at least that seems the case. It's difficult - intentionally, no doubt - to decipher his lyrics. After the full throttle vocals on The Bends, on OK Computer he adopted a melismatic way of singing that slurred the lyrics, and complemented the shady unease of the words. But here he is retreating further, intoning what sounds like cut-up text and there is no help available from a lyric booklet. His voice is treated and shrouded by the mix which reduces his more discernible lyrics to gnomic utterances. The "I'm not here" refrain on the sublime, spartan "How To Disappear Completely", carries an obvious sub text, evoking the image of the child who is convinced that if he clenches his fists, closes his eyes and concentrates hard enough he can make himself invisible.

Kid A is diffracted in content and reads like a sonic scrapbook. Reports that Radiohead had obsessions with early 90s Warp material sketched a picture of a group who had run out of the creative drive that had spurred them on since their formation and were anxiously trying to reinvent themselves - rather like U2 trying to playing catch-up with their peers around the time of Achtung Baby. But this is belied by the opener, "Everything In Its Right Place". A gorgeous vocal melody hovers over chopped up voices, a synth pulse and electric piano in an exquisite cameo. Yorke's proclamation that yesterday he "woke up sucking a lemon", hints at self-deprecating humour, but then again there is no precedent for such frivolity in the group's music. If there is a Warp factor here then at a push the song shares a kinship in feel and instrumentation with Seefeel. The title track is the only weak track on the album. A semi-formed jotting, it consists of a meandering treated voice over more e-piano and a pattering drum program. It takes the computer voice from OK Computer's "Fitter Happier", this time with Thom himself playing the paranoid android and sounding self-important, and unwittingly comical.

"The National Anthem" starts of in familiar Radiohead territory with a syncopated bass and drums lope, and ghostly electronics swirling away in the background in a sort of "Tomorrow Never Knows" kind of way. At least it sounds like electronics, but it was recently revealed that under the new experimental regime, Jonny Greenwood has largely forsaken his guitar for keyboards and features here on the Ondes Martenot, an electronic keyboard instrument augmented by a slide on a metal ribbon. It predated the synthesiser by a number of decades and was pioneered by early twentieth century composers like Olivier Messaien and Edgard Varese A thread of vocal melody is soon revealed as a false dawn as a troupe of caterwauling jazz free-blowers, including a particularly meaty baritone sax, muscle in on the action. It's driven like a wedge through the album and in common with this type of rock-based fusion, the horns sound like they have been grafted onto the rhythm track, with little engagement between the two parties.

"How To Disappear Completely" is the sound of a group etherising before your ears then reappearing swathed in strings and a sweeping, minimal guitar refrain. The song features Yorke's most gorgeous soaring vocals, and is only tenuously tethered to the earth by Phil Selway's mixed down drums before drifting out of sight on massed string glissandi. Their desire for disappearance is granted on "Treefingers", a beautiful slice of chamber ambience that wouldn't have been out of place on Brian Eno's Music For Films.

So far so interesting. This is one of the most eagerly anticipated albums of recent years, but produced by a lesser group, in commercial terms at least, it might have sunk like a stone. It's interesting to read media reactions to an artist or group of this size or reputation on the rare occasions they do something so uncharacteristic - Scott Walker's Tilt, for example - as pundits are then obliged to wrestle with and make sense of music they wouldn't normally allow in the house. That said, reactions have been largely positive with some critics going for it wholesale, even landing on the side of the more experimental stuff. But reading between the lines many are hedging their bets, making sure they're not caught out, to be seen uncool if it takes off massively. There's also a reluctance to slaughter a sacred cash cow - Radiohead on your magazine's cover is guaranteed to sell copies and in times of dropping circulation, that's important.

In these cases approval has been cautiously positive, with a subtext that bemoans the lack of songs and a hope they go back to a more familiar style and bash out some big tunes (even though there is melody aplenty within the supposedly difficult stuff here). Melody Maker took the "If you don't understand something, smash it" stance, putting the boot in and rekindling some of the derision the group had to endure in their early days. Even the hoary old topic of Yorke's wonky eye is opened up in a review that shows just how vituperative people can be when their saviours apparently turn their backs and leaving them feeling there is something going on that they can't comprehend. But as Captain Beefheart advised with regard to the far more daunting structures of Lick My Decals Off, Baby; put it on, clean up the house and let it come to you. And it will.

Structurally there are parallels to be drawn with David Bowie's Low. Personal memories re-emerge of the soul boys at school who had been totally taken by its predecessors, Young Americans and Station to Station, enjoying the grotesque, emotionally-numbed disco mutations on side one as at least these sounded a bit like the stuff they were used to. Then they laughed aloud at the instrumentals on the second side, pronouncing them "crap". Consciously or not, Radiohead have reversed that programming, kicking off the album with a number of instrumental ideas and song fragments in a move they must have known would alienate many, before revealing a cluster of developed songs half way through. An interesting idea - and the group themselves had arguments about the running order - but a more integrated approach would have given Kid A greater coherence Yorke's wish to both disappear and chronicle the process also mirrors Bowie, who in his mid-70s coke-phase almost did disappear, artistically and physically. And although he hadn't got much to say circa Low, he had a desire to say *something* - although it was couched in a delivery so full of blanked-out ennui that many listeners found way too cold. And when Kid A's 'real' songs appear they have a vagueness about them, but are the equal of anything the group has attempted before. "Optimistic" is the nearest they come the album's predecessor, with tom-toms and bass laying out the ground pattern and Jonny Greenwood's guitar reasserting its presence, before unfurling into a sublime chorus with the drums opening up. Yorke throws in the line "big fish eat for everyone", possibly echoing the Brueghel engraving, "Big Fish Eat Little Fish", which, based on a Netherlandish proverb, depicts a gigantic fish being hacked open on land and scores of smaller fish spilling out. It might also just be a neat line that means nothing in particular.

The stunning "In Limbo" follows, with baroque guitar patterns in three time cutting obliquely across the syncopated 4/4 rhythm for the duration giving a supple, constantly shifting perspective. In structure, it is bizarrely reminiscent of Pentangle, of all things, and is garnished with a delicious vocal melody.

Riding out on a double-speed hip-hop groove straight out of the Autechre text book, "Idioteque" is a guitarless creation on which Yorke is heard claiming, rather unconvincingly, "I laugh until my head comes off". Whatever, he soon comes up with another succulent chorus backed by poignant autumnal keyboard counterpoint and is positive and effusive enough to start yelling "this is really happening", and although one doesn't know what that is exactly, it's hard to disagree. That positivism is carried on through "Morning Bell", another bass drums and keyboards excursion with Greenwood's guitar letting in a crack of light into the choruses after the monotonous verses, then picking atonally and sliding up the neck at the close.

The disarming "Motion Picture Soundtrack" signs off. First in is a creaky pump organ, or perhaps harmonium, which acts as a launching pad for a glorious amalgam of choir and harp glissandi that is pitched somewhere between a melancholic sigh of almost cosmic beauty and "Somewhere Over The Rainbow". Radiohead have embarked on a voyage that is for the moment heading further into inner space, an area that they appear to be finding far larger and less fathomable than they could have realised. And it proves not only that the songs are there when they want to write them, but how good they are in being able to withstand these treatments.

This could be a stop gap to let them get the weird shit out of their system before making another album of the songs they have been playing live recently. Let's hope it's more than that. And forget about Prog Rock, a tag which has always been stuck on them lazily and inappropriately. This melodic mix of texture, timbre, ambience and disturbance shows if they can fully integrate all the elements, they could come up with something truly mind-blowing. Reading the pre-release hoo-ha prior to listening to Kid A, it seemed likely they were perversely refusing to playing to their strengths. But their strengths may turn out to be quite different from the ones we used to attribute to them.

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