I've played the first Splinter Cell, Chaos Theory, and Double Agent. I enjoyed Chaos Theory the most because I found it more forgiving than the original, but still true to game play that made the first game great. I also liked the option to choose action or stealth in almost any situation. There was great variety in all of the locations and all of them were interesting. Furthermore, I really enjoyed the campaign coop from Chaos Theory. I would have liked to see it explored more extensively than it was. I disliked Double Agent because I'm not really interested in Sam Fisher having to deal with moral dilemmas.
In the same way, it will take some work to convince me that Conviction is a step in the right direction. I prefer Sam Fisher sneaking through government facilities, stealing secrets, recording vital conversations, and kidnapping or killing political characters. I'm not really interested in him smashing a thug's face through a urinal.