Tracks range from semi-ambient IDM to D&B styles such as dubstep and "drill and bass" (i.e., less bpm, more complexity), with occasional patches of experimental, and one electropop track ("Sixty Forty" by Broadcast). There's only one real loser track on the disk (in my not-really-very-humble-at-all opinion): "Elecktroids Bonus Circuit" by Elecktroids is a tediously repetitive, dry riff on a drab theme. Fortunately, the rest ranges from really quite good to excellent. The other artists represented (the ones that don't suck) are: Boards of Canada (there's an interesting story behind this name for a Scottish duo!), Plaid, Autechre, Clark, Nightmares on Wax, Flying Lotus, Broadcast, and Seefeel. I have albums from BoC and NoW, and thanks to the format of this disk (all unreleased stuff), there is no overlap at all with other CD's, which is also a nice plus for me when I buy a compilation.
Warp Records has been around in this genre for a looooong time, and hasn't lost its underground feel. According to Wikipedia, their first release (in 1989) was "financed by an Enterprise Allowance grant and distributed in a borrowed car"; it doesn't get much more underground and indie than that!
The cover art is also interesting: it may well be a shout out to Nick Warren's Back to Mine ambient/chilled mix compilation (the very first album in the Back to Mine series), which I quite like, but which doesn't seem to be that well-known (Wikipedia doesn't even mention his ambient stuff, despite this mix and the ambient mix on CD1 of Global Underground 030: Paris).