I played it a little at the PSE (PlayStation Experience), the UK equivalent of E3 (PS2 and PS1 Only) last year (it was barely an alpha then) So i've got a bit of experience with it.
I'll compare it to Halo seeing as it was described as the "Halo killer" at the time, though Halo II is out now
The graphics are quite realistic in the sense that they're down to earth and gritty. It lends the game a sense of realism that Halo lacks. If this is important to you in a game then you won't be dissapointed.
The control system is your standard PS2 FPS, near identical to Timesplitters but with jumping. Responsive and sensitive, no problems here. I have no idea what the story is, something about aliens I imagine, I only got to play part of an incomplete level. Can't comment on the sound because off all the frickin' external and white noise (apparently PS2's in the walls are better than booths).
The meat of the game is as always the gameplay, and it's pretty straightforward, pick up guns, shoot stuff. As the name implies, there is a lot of shooting in a relativley small area which makes it very hectic at times. The enemies react to being shot, mainly by dying, the AI at the time was rubbish, hopefully that's been fixed. Also it's fully network and internet able which rules.
It's probably changed a
lot in a year so nothing I say here can be 'true knowledge' but my impressions of the game back then where that it was good and is getting better. Halo beater? Maybe depending on your outlook (if you like shooters to be more realistic or hate Xbox/Love PS2 then change this to a yes) But I don't know if it could knock Halo II off it's pedestal, and it doesn't touch Half-Life 2. Speaking of which, it's out!!
Hopefully this gives you some more insight into the game, I will be buying it after i'm done with HL2 and San Andreas...and MGS3...and Budokai 3...it'll probably be platinum by then