Hard to say anything good about this game
Well, THQ didn't do it right.
Graphically, the game is nothing to write home about. The environments are not particularly realistic (and by the way, I have played real paintball many times), and the characters are generic. You can choose male or female, and that's about it.
Sound effects, naturally, are not great. The dramatic effect of a paint splat isn't exactly operatic.
Playability is where the game suffers. There are two problems.
First, and this is extremely common in FPS in the PS2 era, the computer opponents are crack shots who never miss. They hit you while you're hiding, crouching, shooting, looking for them etc. It's difficult to get any kind of momentum going because the CPU is continually schooling you. As well, the CPU is VERY cheap. During one match, the CPU enemy stood near the spawn point and shot me three times as I tried to re-spawn (meaning the CPU scored three points which, in a 30 point game, is a fair bit). In a real paintball match, you're not allowed to do that.
Second, your character moves painfully slow. The game does not give an accurate depiction of what paintball is like. It really gives more of a depiction of what poor programming and design results in.
It's obvious the guys who made this game have never played paintball, and don't know what makes it fun.
I would give this game a overall score of 1 out of 10, mainly on the strength that the game is reasonably priced, and is very challenging for someone who enjoys a slow-paced game which cheats to win.