Two thumbs WAY up!!!
First of all, the game play is excellent: moving, shooting, buying weapons, etc.... You can't move while you are shooting unfortunately but it's forgivable because the enemies don't usually move to fast.
The graphics are really good for a PS2 game. It is very satisfying when you shoot the head of an enemy and you see it blow off.
The sound is pretty good, the merchant gets a little repetitive at some times. The music is good, so are the sound effects.
This game just has a ton of re-playability, with the new difficulty level, extra mini-games and to max out all of your weapons.