AWESOME. I wish everyone would stop comparing EVERY game on the Playstation 3 to Call of Duty 4: Modern Warfare. It's ridiculous, yes COD4 is absolutely AMAZING and probably the best game on PS3, but Splinter Cell Double Agent is an amazing game in itself.
Firstly the graphics are intense and crisp. Every character and piece of scenery is beautifully designed, and the game-play is incredible. Definitely the best Splinter Cell installment so far! Very tense moments in seemingly impossible to succeed conditions makes this game really challenging (yet not too challenging to the point of frustration!). Stealth techniques are very realistic and the enemy A.I. is very accurate to what you'd expect in real scenarios.
The only thing is that some people might not enjoy the strictly stealth aspect of the game. This isn't about running in and killing everyone in an orgy of destruction, it's all about patience. Timing and strategy are the keys to success in this game, so I think it's understandable that some less enthusiastic players will get possibly bored eventually.
That said I would recommend this game to everyone who is a fan of warfare and/or shooter games, because this one is definitely not a game you'd want to just ignore without at least playing it!
Overall: Visuals - 10/10; stunning!
Game-play - 10/10; personally I love it!
At least rent it!!