I loved it.
From start to finish I loved it. The visuals were spectacular. Light cycles and other vehicles were exciting and very fun. The mythos fits nicely with the established Tron mythos. It was of course not exactly the same feel as Tron. It was different where it needed to be. Where Tron tried to give as much homage to computer vernacular of the day, Tron: Legacy does very little of that, which follows since the grid in Tron: Legacy is an entirely new computer system which has operated independantly for the past 25 years, all on its lonesome away from the rest of the world that was converging on the Internet.
It was a spectacular movie from start to finish.