The first track of Radiohead's newly released In Rainbows, "15 Step," starts with a lonely digital rhythm loop soon joined by a thin vocal line from Thom Yorke, coldly reminiscent of his 2006 solo album, The Eraser. Forty seconds in, a lush guitar part from Jonny Greenwood asserts a much-needed layer of humanity, and by minute 13 the rest of the band completes the soundscape with bass and drum. Radiohead has returned.To recap briefly, Radiohead has been working on this, their seventh album, since at least 2005. Last month guitarist and general music innovator Jonny Greenwood dropped word that the band had completed the album and still lacked a record contract. Oct. 1 rolled around and brought with it an announcement that the album would be released via the Internet in 10 days' time with no set price; it is essentially a free download with the option of a donation.

It's difficult to overstate the utterly revolutionary implications of this release model. Radiohead is the first major act to embrace the changing tide of the recording industry fully and accept the merits of file sharing rather than fight them. While the henchmen lurking at the Recording Industry Association of America are doing everything in their power to deter free music distribution, Radiohead has proven that it can be an ally to musicians.

With all the obvious accolades and appreciation we can pour over this bold and enlightened move, it seems likely that discussion of the album will be dominated by the ingenuity of the release. And yes, this point does rightfully warrant much focus as the release of In Rainbows will probably be looked back on as a major turning point in the history of recorded music. However, when taken in its own terms as strictly another Radiohead album separate from its business and marketing aspects, the album should speak for itself as a piece of musical output from a group of artists. Bearing this in mind, In Rainbows is indeed a great album, an album that genuinely maintains Radiohead's reputation as the most inventive, relevant and all-around brilliant band in the world.

What separates In Rainbows from Radiohead's other albums is simple. With the debatable exception of 2003's Hail to the Thief, each Radiohead album since Pablo Honey (1993) has been a giant leap forward, particularly in terms of the band's maturation in experimental structure and textures. Ok Computer (1997) was more daring than The Bends (1995), and with the status-quo-shattering combination of Kid A (2000) and Amnesiac (2001), Radiohead achieved the highest possible expression of art within the medium of rock. Even Hail to the Thief, with its admitted, minimalist ethos, signified a step in a tangible, precise direction.

In Rainbows conversely provides a series of compositions that seem to serve more as a retrospective of places the band has been rather than an exploration of somewhere new. "Bodysnatchers," with its driving guitars and drum rhythms, harkens back to the olden days of Ok Computer or even The Bends. The surprisingly sparse arrangements of "House of Cards" and "All I Need" similarly reflect on simpler times.

Some of the album's most brilliant songs are clear evocations of the complexity of the Kid A era. When I listened to the layered guitar arpeggios that form rich chords during "Weird Fishes/Arpeggi," my doubts as to whether Radiohead was still at the height of their creative prowess melted. And during the somber acoustic guitar and string arrangement of "Faust Arp," I was convinced that this album is as breathtaking as anything they have ever recorded.

While In Rainbows may not seem to have the concrete narratives and clear musical theses of earlier albums, this does not by any means indicate that the band is not saying something with the work. In fact, this point is inherent to the album's message: This very well may be the final Radiohead album. The symphony-writing Jonny Greenwood clearly has ambitions beyond mere rock guitar, and Thom Yorke has already released one solo album. The final track of the album, "Videotape," attests to this. "When I'm at the pearly gates," Yorke sings in the opening lyrics, "this'll be on my videotape." With In Rainbows, Radiohead is quite literally giving its fans a farewell message: This is where we've been, it's been wonderful, and goodbye. The band exits on a positive note; the final lyrics of the album, quite possibly the final Radiohead lyrics ever, are as follows: "No matter what happens now, I won't be afraid / Because I know today has been the most perfect day I've ever seen.