Damn, nice game.
Never had lag problems, and didn't have issues with aiming while moving (WTF?!).
My ONLY complaint is that once you've got a decent gun it becomes way too easy to rack in dough and buy all the upgrades, at which point you don't even have to move and you can mow down enemies before they even get on your screen, all while regenerating your health from any stray bullets/missiles that should possibly hit you. So it was easy, but very very fun. Wish there were more upgrades in the end though (sequel plz k thx!).
Last level threw me for a loop as well.
Overall very good.