Just Sam, better graphics, new enemy, some new feats and just a lot of cool stealth action.
There is offcourse a new story and some new feats like whistling to distract guards.
A bad thing I thought of the game was that there are a lot of missions in the woods and grass wide lands, those are things I personally don't really like in SCPT,my preference is invading a building and crawling trought pipes and lurking in unrealistic shadows.
The story however is really cool, you gotta research a guerrilla leader and stop is actions of rebellion, the first time you get the chance to kill him you don't take it because you first need to know more, trough the missions you achieve this objective, and then at last you may kill the cool looking evil dude with his baret(H).
There are some missions that lead you to Jerusalem when you need to follow a helper to missions in the middle of nowhere where you need to disable the flight of the rebel leader. You need to track his conversations an bug his phones.
There are some new feats like the whistling option but there is also a new laser option on your silenced 9 mm, I didn't really used it because it's harder to aim, but it's more realistic.
Also a new cool feat is the sitting between walls and then jumping on the a higher one,and offcourse a really new cool something is the online gameplay, but I can't tell you anything about that because I wasn't able to play it.
A thing I think is really bad about the game is that they gave Lambert a new voice, maybe the old Lambert is dead or something but the new one is not cool.
All together the game is quite cool but much like the previous one, the real changes of the serie of Splinter Cell come in Splinter Cell Chaos Theory, read my review about that game!