1) The Grid is too real.
The Grid is not the Matrix or even the Matrix’s Construct. It is not a simulation of reality, it is a metaphorical representation of emergent behavior (unintended consequences) within computer software. In the original movie, the computer world is obviously computer-generated. The rotoscoped actors floated in a sea of special-effects. The effects were twitchy, and you could tell they held Frisbees and wore spandex, but through the magic of suspending disbelief you would see the circuits and the flowing energy. It was constantly obvious that it was not supposed to look real. Tron: Legacy’s choice to go with beautiful but often realistic CG environments and practical effects for costumes destroys this. The entire movie is real actors in real glowing clothing walking in (due to our advanced CG technology) physically-real-looking environments. It doesn’t feel enough like we’re in another universe, it just feels like we’re looking into a club that’s too fancy for us to afford matching costumes. It looked real, and there was no disbelief to suspend, no reason to take your mind where they wanted it to go. It felt better when they were playing games, but again, the breaking glass and bodies and machines disintegrating into physical fragments were choices that make the world feel more real, more solid, and less like another universe with different rules.
I am not saying the original makers of Tron wouldn’t have made the same mistakes presented with today’s technology, but they couldn’t and didn’t and now we have our reading of the original film to inform our decisions about how to make a sequel. (And I would argue that the choices they did make among the techniques available to them does suggest they intended and desired the otherworldly-feeling they achieved.)
The flashbacks to Flynn in leather jackets on the Grid just made me roll my eyes.
2) It is too long.
While there were a few unnecessary scenes in the original, this movie at times felt interminable. People talking about things we don’t care about often in ham-fisted attempts to evoke the original film I can do without.
3) It isn’t a good sequel. (Spoiler + fanboy alert.)
The characters and motivations don’t make a whole lot of sense coming forward either in or out of the computer. I’m not convinced Flynn would be motivated only a year or two after becoming the helicopter-flying, Wall Street suit-wearing CEO of Encom (as he did at the end of the original movie) to go back into the system and “create a perfect society.” I’m even less convinced that after fighting the MCP he would be so naïve as to create such an obvious replacement.
Moreover, since we eventually learn that TRON still exists, the place where Flynn goes to do this was either the actual network at Encom (which is doubtful since the monumental changes wrought would presumably have destroyed the day-to-day functions of the company) or a copy of the entire system that lives in the basement of the arcade. Sure. And what about TRON? TRON’s purpose was to restore the freedom of the system. What justification are we given for his conversion?
Even harder to understand is the manner in which Flynn (even with Yuri’s help which he did not seem to have) could develop a way to make the laser work backwards and create humans out of programs.
The original CLU program was deleted by the MCP; it isn’t clear to me why Flynn would name his new doppelgänger after a flawed hack. (I could see him naming it after his son or a trusted friend of one of his Zen masters.)
In the original movie Flynn interacts with the programs written by his friends in real life. These programs reflect the personalities of their creators which is often cute and touching. This aspect is almost completely missing in the sequel. Though they go through the trouble of introducing several new real-world characters, none of them show up as programs on the Grid. Due to the vagaries of the story, this is true even of Flynn, who is three different people in the film, none of which is a direct real/program parallel.
The movie has flashbacks that bear no resemblance to the original movie. There isn’t even a hint that the world we see in the new movie evolved from the world we saw in the original.
4) Sometimes the movie doesn’t even try.
Would it have been so hard to show us Quorra* and Sam materializing back in the real world?
* I had to look up Sam’s name (since I cared so little about the brat) and saw the girl’s name wasn’t spelled ‘Cora’.