A finely-crafted sequel
The action is a lot like the first Headhunter- third person shooting, some optional stealth tactics, and brain-squeezing puzzles that sometimes feel a little out of place. Gone are the motorcycle bits from the first game, but that's okay, since they didn't control very well anyway. The biggest gameplay changes though are a metroid-like scanner that helps with puzzles and a reticle that shakes if you try to target enemies while moving. This latter change will turn some people off, but for me, I was thankful for the skill it took to pull off shots on the fly, and it gives a very satisfying umph! to the action.
The graphics have a cool glow to them that takes away some of the rough edges, but they're still on the higher end of the PS2's graphical powerhouses. The voicework is great and well-acted, and the music is so good that I bought the soundtrack. You might hunt it down too once you play the game.
Overall, there's a ton of solid action here that doesn't feel too much like you've played it before, even if you've been playing similar games like Resident Evil 4 or Metal Gear Solid 4. And it's dirt cheap now, so do yourself a favor and pick it up.