I just got back from seeing this, and I thought it was amazing. I'm not one who highly values the plot in films anyway (if I want a good story, I'll read a book) so I only ever really look for the visual and sound aspects, and Tron delivered on both of those perfectly. The setting and visuals are amazing; I've been sceptical of the whole 3D thing as being nothing more than a gimmick ever since it came out, but this film totally changed my opinion. Instead of making scenes purely to show off 3D, they used the 3D to compliment the film; it was just a nice aspect that added to the already stunning visuals, rather than being shoved in your face every 5 minutes. It had everything a sci-fi setting needed, lights, futuristic design, dark atmosphere (with rain!) and I could see the influences from the 80s as well, so it had a retro feel as well as the futuristic one, which I absolutely loved.
The soundtrack was brilliant of course (it's by Daft Punk, how couldn't it be?) and they proved that they can go out of their comfort zone and do some orchestral work, and even manage to mix it successfully with the house music they're known for. I loved the club scene with Derezzed playing.
My favourite movie of the year.