The music on the soundtrack is wonderful and is capable of standing out on its own merits. The soundtrack is a great fusion of classical music and techno. Track 18 is my favorite piece in this mix. Do be wary that the soundtrack is not a complete compilation of all songs featured in Gankutsuou. The Classic Compilation also contains some classical pieces featured in Gankutsuou.
Gankutsuou Original Soundtrack
This is, hands down, my favorite anime soundtrack that I've purchased this year. Koji Kasamatsu's orchestral soundtrack for "Gankutsuou" evokes all of the emotions of the series - joy, pain, loneliness, anger, the Count's thirst for revenge - and it's great to listen to even without accompanying the anime, which is a rare feat for a sountrack. Jean Jacques Burnel sings on two very, very different tracks - "We Were Lovers" is an achingly lovely piano and orchestral piece, wherease "You Won't See Me Coming" is more of the punk rock that he's known for. Oddly, this soundtrack includes both the TV edit and the full version of "You Won't See Me Coming." I'd recommend this soundtrack even if you haven't seen "Gankutsuou." Yes, it's THAT good.