Tested on a MacBook Pro (128 MB RM X1600, 10.6.6) and a MacBook (GMA 950, 10.5.8). As with Alien Shooter, AS2:R has some moderate graphical issues to consider, notably horizontal lines in the screen during play, and texture smearing. The issues are enough to be noticeable, but certainly not enough to make the game unplayable (I'm currently on Mission 9). For the most part, I've experienced best performance with detail settings set to low, shadows off, and screen resolution set to 1024 x 768.
Also, as with Alien Shooter, I had too much fun to notice the glitches. And I still don't know why it's called "Alien Shooter" when the monsters still are made out in the plot to be little more than creatures cooked up in a lab.