(Very) Short review of three that I played last night:
Nitronic Rush- I think I would like this if I had an XBox360 controller. It looks really fun, but it just doesn't play well with the keyboard. I tried to get my PS2 controller to work (with my USB adapter and Joy2Key) but that didn't work very well either.
I couldn't figure out any way to get it to work with my gamepad by default, it seems to only work with 360 controllers, which is a real shame.
Celestial Mechanica - I enjoy Metroidvania games, and this has elements of that and VVVVVV, which I am a big fan of as well. My main complaint is that it was far too short (beat it in under 2 hours) and the vertical scroll is poorly implemented. I suppose it's the sort of game that you are supposed to do speed runs with (and no-death runs), but I don't do speedruns.
Abobo's Big Day Out - This game I feel is only there to appeal to nostalgia. While each segment is fun in it's own right (I liked the Legend of Zelda segment), it makes me want to go play each original NES game rather than this. For what it is (a tribute) it does it well, but I wouldn't go and play it for the gameplay. Play the originals.
I haven't tried the two survival horror games in the bundle. I'll probably try the Ascension one first (that is if I can get an unbroken zip file), since I am a big fan of the Resident Evils prior to 4 and Silent Hill. I'm not sure if I'll try imscared, because I'm not a fan of the Amnesia/Slender type survival horror games.