From cover, you can safely aim at bad guys without worrying about damage. Combine this with the fact that your first bullet is always dead on no matter what gun you're using, along with the general lethality of headshots, and you'll have no trouble making short work of the legions of foes who throw themselves before your crosshairs. As you get used to the game, you'll become a pro at lining up headshots with pretty much every weapon, and deftly plunk several enemies in a row with single-shot kills. Part of this is due to limited enemy artificial intelligence. (They prefer to stand in the open and shoot.) At any rate, you still feel like a hotshot.
The only real problem is that one button shares two functions: changing weapons and changing firing mode. Late in the game, you'll need to throw grenades and then quickly shift to a high-powered submachine gun to subdue the toughest foes. In the process, it's easy to mistakenly switch the gun to single-shot and waste a very valuable window of opportunity. Aside from this one hitch, the controls are smooth.
The game controlled well on the PSP, and you get more of the same on the PS2 version, but surprisingly enough the game also looks good. After all, a big part of what makes PSP graphics seem pretty is the tiny resolution, but Dark Mirror reflects nicely even on the big screen. It isn't visually spellbinding or anything, but the frame rate is steady, and the visuals are clean and clear. The voice acting, on the other hand, is strictly second-rate, and the music is rather unmemorable.
If this were the PSP version of Syphon Filter: Dark Mirror, we'd talk here about the awesome multiplayer content. Considering that there isn't any in the PS2 version, we'll instead talk about the fact that the campaign is a little less than 10 hours, and isn't particularly worth replaying. It also isn't worth the 40 dollars the game costs new. The single-player is fun, but it was more fun when it was attached to the superior PSP game.