The film started out great, except for an annoying motion capture rendering of Kevin Flynn (Jeff Bridges), but once the movie got into the computer world I could not help but feel that I had seen it all before (in the original Tron). The characters follow nearly identical trails, starting with getting set in the game grid, escaping and ultimately riding a ship down a beam of energy to get to the end game of the story.
Michael Sheen's Portrayal of Zuse was over-the top camp which did not fit with the style of the rest of the film.
Motion capture is fine when the whole film is generated in this fashion. I could even accept the computer version of Kevin Flynn, known as Clu, as a motion capture version of Bridges to differentiate between the two realities (although all of the programs would then need be portrayed as motion capture renderings also in order to maintain symmetry). But using a motion capture version of Bridges to portray the real (younger) Kevin Flynn both inside and outside the computer world did not fly with me and will not do so until the graphics can reach a point where the face can actually move like a normal face when talking. In the mean time it is just an annoying feature which pulls me out of the film.
On the up side, I was pleased that Bruce Boxleitner returned for the sequel. And his motion capture version, Tron, was kept in dimness and in the background where it was not nearly as obvious and annoying as Bridges' motion capture Flynn/Clu.
Tron: Legacy was still good enough to be mildly entertaining. I'd say it is barely worth renting at full price. (C-)