Less nerd friendly reviewers have said it's dreadful, they hate it, and would rather be de-rezzed than subjected to it again. Invariably they point out something to the effect that the first Tron was a flop, loved only by a small sub-culture of spazzes and nerds.
Now, if there were a wikipedia entry for that small sub-culture of spazzes and nerds, I'm pretty sure that I'd be the demo picture. I loved Tron. I mean I looooooved it. I made a Tron outfit for Halloween that year out of white clothing, a bike helmet, a frisbee, and blue electric tape. I was decades ahead of "Tron Guy", by golly. So when people trash the original Tron, I think they're just humorless muggles. Then again I haven't seen it in ages, since Disney has been systematically making it unavailable.
Historically, Hollywood crushes nearly all my cherished childhood nerdthusiasms. Narnia has been resoundingly mediocre, the new Star Wars movies were an untrammeled obliteration of everything about Star Wars that was beautiful, Transformers sucked, Spider-Man, Iron Man, The Hulk; with the exception of Lord of the Rings, it's all been crap.
Odds are long that Tron will be awesome. But hey, Daftpunk did the soundtrack, so at least there's that!