Chaos Theory was easily one of the better Splinter Cell games. The storyline was great and Ubisoft improved on a lot of the older two games' mechanics without changing a lot of things that didn't need changing. (Read: Don't fix what isn't broken.) Unlike what Ubisoft did to my beloved Rainbow Six after Raven Shield... but I won't go into that here. ~_~
Back on topic. I'm with Frank here, if you like stealth-action games, then you'd probably really enjoy this one, and the price is really good.
I used to have this on Xbox. Coop was so fun...this game was great.
*optic fiber through door, see enemie's feet*
SLAM!
*close door, other person walks up to dead body*
"Oh, man, I don't wanna end up like him."
SLAM!