Have just come back from seeing this. 3D doesn't do a hell of a lot for me, so I opted for the 2D version on a huge screen. Although I concede that the light cycle sequence would look great with 3D.
I only just revisited the original a few weeks ago, having not seen it since it was at the cinema. Even so, having a mind like a sieve, I only caught one incidental reference to the old movie (a line that was used, obviously things like light cycles and that light beam train thingo are references too, but you know what I mean). I was also hoping to spot a pacman or mickey mouse easter egg, but didn't. Maybe Namco wanted good money for it this time, where as last time I bet they didn't get anything. Or of course, just like when I watched the first movie, I just didn't notice

This time around, the story I think is more thought out. The original really was about 'hey, we can do some freaky computer effects no one has ever seen before. Oh, and we should put a story in there too'. Actually, the original idea for the story is quite profound really. Just that this time, they spent more time on the detail I think. So what do I think of the CGI this time around? Well, I'll start by saying that if I had rated it out of five back in the day, the whole of the original movie would have been a 5/5. It was that astounding. But watching it now, to me the CGI is still 5/5, but the rest a lot lower. This time around, with Tron Legacy, the CGI isn't as mind-blowing (how can it be?). But to pick a fault (in my eyes, others will feel differently) I would say that the original look of the CGI, with it's Giraud shading, perfectly felt to me then and now, how that world would be. This time there is more texture, and skin stuff (dunno the technical terms, sorry!). And tyre smoke! This just doesn't seem to me to be how this world would be. It didn't eat away at me though

Also slightly disappointed the tanks weren't featured. The original tanks looked amazing with their asymmetric turrets. think I saw an aerial view of one but that was it.
Some VERY impressive CGI though is making TRON and CLU look like they would have in 1989. It was amazing to see a Jeff Bridges as if he'd just finished filming Tucker or summink. I bet he's wishing he could keep that look. But then probably not, he seems the sort of guy who is extremely comfortable with who he is and how he is aging.
A few scores here to compare methinks
Tron (if I had rated it in 1982) 5/5
Tron (after rewatching it recently) 3.5/5
Tron Legacy 4/5 (but I bet if I watch it 28 years from now, it'll still be 4/5)
my score for recent movies you may have seen:
5/5 - Michael Clayton, In Bruges, Gran Torino, Mary and Max
4.5/5 - Taken, Iron Man, Reign Over Me, Watchmen, The girl with the dragon tattoo
4/5 - Tron Legacy, Traitor, Bedtime Stories, Sunshine, pineapple express
3.5/5 - 300, Max Payne, You dont mess with the Zohan, Yes Man
3/5 - That new Indiana Jones flick, Disturbia, That new TMNT flick,
2.5/5 - Angels and Demons
2/5 - The Love Guru. Note: My 2 is probably someone elses 1. Just leaving room for worse!