I managed to get my hands on a copy of Dark Void today.
Quite a difference from the demo and I'm enjoying it very much. If you have the means I highly recommend picking it up.
First off the demo mission is about twice as long as in the demo. It kind of takes a bit for the game to get going but once you pass the demo mission it really picks up.
I've been able to get the controls just where I want them. Yes, they are bit hard to get accustom to but after some time it becomes very easy. If you twitch the mouse in one direction it will continue in that direction until opposite force is applied when flying, it's not that hard.
With the game set on High PhysX it's quite a treat. Dudes falling past you disintegrating into a mass of partials during vertical game play is nothing short of amazing. Rock particles flying off walls is also quite a site. I'll have to get some screen shots taken at a nice resolution but it has to be seen in motion to be appreciated.
Anyway, not a bad game at all.