No-drug-only-demo-impression:
Maybe I just don't get it, but the demo left me entirely unimpressed. I mean, it's beautiful and all, but feels kind of unfinished. Yes, at Insane the Pacmen shoot at me and spawn like mad, but that's pretty much it. Still feels like someone took some Winamp Visualizer, added a drop of Elite/Wingcommander/whatever - and janked out the fun. I feel like you just fly around and pick up items and powerups without any real motivation.
I guess it's fun for a tenner, and even moreso after it's gone on sale for five cent or something at the upcoming sales*. With drugs this might break some brains I guess.
*speculation. Might or might not happen.