Various Artists

As a soundtrack for his forthcoming Bob Dylan movie I'm Not There, director Todd Haynes has assembled an impressive array of musicians young and old to provide cover versions and re-workings of their favourite Dylan tracks.

Much like the Wylde Rattz project for Hayne's previous rock biopic Velvet Goldmine, supergroup "The Million Dollar Bashers" (featuring Lee Ranaldo, Steve Shelley, Nels Cline and Tom Verlaine among others) back many of the singers, and were put together to bring some cohesiveness to the album. As a cohesive album however, I'm Not There fails conclusively. Clocking in at a whopping 160 minutes, the jam-packed double CD is simply far too long - eclipsing the sprawling White Album and making Red Hot Chili Pepper's 2006 opus Stadium Arcadium seem like a couple of bonus tracks.

Taken as a collection of individual tracks however, the album provides a wealth of ammo for the mixtape masses with more than a few silver bullets in the arsenal. With such great material in the hands of these artists it would have been a tragedy for this album to be a faliure, but cover songs have always been a hit or miss affair - with the artists often taking one of two methods of attack when approaching the material. The most effective method here seems to be the straightforward approach, letting the bands own sound soak through the material. Sonic Youth's understated cover of I'm Not there is a highlight, as are Steven Malkmus' multiple contributions adding only a few restrained theatrics to produce some of his best work.

Black Keys provide one successful modernisation with their fuzz metal version of The Wicked Messenger, but The Hold Steady's version of Can You Please Crawl Out Your Window tries too hard to fit Dylan's square song into the band's story-telling style of a round hole. Not to mention Sufjan Steven's overblown theatrics, which make Ring Them Bells (what else?) smugly saccharine. Eddie Vedder's All Along The Watchtower would make for a live concert highlight, but it sounds pretty straightforward here  - as does Cat Power's solid, but karaoke-like cover of Stuck Inside of Mobile - following Dylan's version down to the tiniest vocal shift, in a way that even he refuses to do in his live show.

Some minor disappointments come from artists who have covered Dylan's work so well previously - such as Pearl Jam's version of Masters Of War or Jim James' superb Billy 4. Jim James covers Goin' To Acapulco on this album, which is a mild let-down when My Morning Jacket could have done a blistering version of something like Hurricane - particularly after they so perfectly blended their own heavy rocking style into Freebird in the woeful Elizabethtown movie.

For all of this, it's the breadth of Dylan's songwriting that is the star of the show - with 70's cowboy-era Dylan coming out particularly well. Calexico's multiple contribution's provide much of that, as do Los Lobos' spirited break for the border with Billy 1. It's when the musicians' really grasp the spirit of the songs that things really work - and while Cat Power's uninspired rendering illustrates Dylan's occasionally drawn out verses, John Doe's version of Pressing On and Ramblin' Jack Elliot's guitar picking on Tom Thumb's Blues provide a celebration of the music itself, rather than just the lyrics.

34 tracks picked from Dylan's catalogue of literally hundreds is in itself quite an achievement, resulting in an album so dense that it's taken me an extra week just to get to grips with it all. If it was actual Dylan versions it might be up their with Mothership in this year's best of (disqualified on a best-of technicality). And in fact, since hearing this album I have drawn up such a playlist, which is working out nicely.