Xbox Live addition=better Splinter Cell
Pandora Tommorrow, while didn't overly impress me in the single player, has a phenomenal multiplayer via Xbox Live along with co-op play. Xbox live plays as spys vs. mercenaries and each team has it's own advantages. It brings stealth online and is very fun. Single player has way too many try and die situations, but it isn't overly hard either. It can get frustrating many times because you'll pull out your gun, shoot an enemy and then hear "Fisher your not supposed to do that, this is stealth. MISSION FAILED." Something like that.
The graphicsare simply amazing, the intro scene looks awesome, the game is very, very realistic looking making it the best visuals on Xbox of any game before this, until Halo 2 and Doom 3 came out, this was the best looking game on Xbox. Only thing that brings it down is the lighting effects, because it's too realistic get in the way a lot, almost forcing you to be in night vision for a majority of the game.
With the online multiplayer, this was really worth the $6.99 I paid. If you're interested in single player, stick with MGS. It's not bad at all but I just suggest MGS over this. Expect a very tactical and realistic game that is also very fun and challenging to play. A lot of try and die situations, but an awesome game none-the-less.