Let's start off this review then. The build up is very nice and effective, but I think it may have dragged on a bit more than it should have. I started to get bored after 1 minute of build ups.
The transition between the ambient it a little bit to sudden I think. It all seams to happen within the space of about 2 seconds. Although it's nice to have a change from the ambient fade in's.
The dubstep could do with a little more work and variation I think. Nice drums but I just don't think it's deep enough to be a D&B tune. I think this really should go in under ambient rather than Drum and Bass.
The transition from dubstep to ambient at the end was a bit sharp to, no real build up.
It's not bad though. Fairly creative, it just lacks certain things that should make it into D&B tune. Replace it into ambient, and you've got a top tune there.