The core gameplay was decent enough, the framerate/port job was craptastic. Also, some of the levels were less-than-enjoyable. Some especially grating moments went as follows:
Going through dark-as-shit corridors with marines, blasting baddies, generally having fun. Get to a certain section, then marines say "lol we'll kick it here, but you alone must venture forth into the dark and turn a switch on or bring back some piece of shit." I then gotta go through more dark-as-shit corridors, this time alone, where of course there are typical monster-closet ambushes waiting for me. NO FUN.
Quake 2 was a great little bonus, but the controls were not as tight or smooth as Quake IV's (WTF, for shit's sake?), so it killed any fun I could've gotten from it (kinda like PDZ, another 360 launch 360 shooter I was playing at the time).