Played Splinter Cell: Conviction for good 4 hours and here are my impressions:
Gameplay: It has changed a lot from the previous Splinter Cell games. They have completely revamped the gameplay mechanics. In the earlier Splinter Cell games you could complete a mission without killing a single person but it's not the case here. You wanna move forward, you gotta blow some brains out. It's a mix of stealth and action. SC: C for me is MGG4 + FUN (yeah MGS4 wasn't fun at all). So, all those who are reluctant with this title shouldn't worry cause the gameplay overtly stealthy this time. It's up to you how much you shoot and how much you sneak but you gotta shoot. All sneaking and no shooting won't get you anywhere with this one. Weapons are good. Not great but good. Gadgets are awesome, EMP grenades, portable EMP, sticky camera and all that high-tech Third Echelon merchandise. Overall the campaign is fun but really short (5-6 hours). I think I'll be done with this one today itself.
Graphics: Nothing different from what we had in Assassin's Creed 2. I won't say jaw-dropping but just enough to keep you glued to your screens. Performance is choppy though. I'm playing the Xbox 360 version and the frame rates are very inconsistent. The game even starts to lag at times when there are explosions. PC version will definitely have much better graphics with full HD resolutions and other enhancements.
Story: This time around, Splinter Cell story is interesting unlike previous games which had mediocre plots. I won't say much here because there are some heavy spoilers for those who have followed the previous SC games.
Audio: Soundtrack goes really well with the situations and the voice acting is great too, especially for Sam Fisher. Not much of an audio expert, so I'll leave it up to you to decide.
I'd recommend this game to anyone who can get their hands on it. Do read the wiki for previous SC stories though. Otherwise you won't get a jack about the things going on.