Really Nice
Yeah, the physics were a bit clunky, but I'm not sure that really detracted from the game. Nice and addictive for a while, though things start getting a bit repetitive by Level 10.
Nice to see new enemies at every level, and the power-ups were nicely done. I especially like how you can add the power ups together, which is rarely done so effectively. With several gun types paired together, you can clear a lot of enemies in a hurry, but you have to hurry because they time out. Nice touch.
Overall, a very well done game.