It's hard to rate the Tron movies, to be honest. The first one was one of my favorite films when I was a kid, but as an adult it's kind of cheesy and slow-paced. The second one was beautiful but exposition-heavy and sort of pointless. Despite all their flaws, there's a special place in my heart for the Tron universe.
Ares is also heavy on the exposition, but it doesn't feel as ponderous as the previous films. At its core, it's about two rival corporations, fighting over a piece of code that will change the world. The evil corporation, headed by the grandson of the original movie's antagonist, doesn't care who gets hurt as long as they make a profit. Meanwhile, the good company wants the code for completely ethical purposes, such as ending world hunger. It's sad that in a story about living computer programs, an ethical corporation is the hardest part to swallow.
The special effects are absolutely stunning. I saw it in 3D, and I highly recommend it. The visuals are easily the movie's biggest draw. Unfortunately, once you get past that, there's not a lot to say about it. I loved the nostalgic references to the original movie, and it had some really pretty action scenes. I also like that it spends plenty of time in both universes, with AI machines getting 3D printed into ours.
I love the little touches, like how the vehicles are printed with supports like a those from a filament printer. Or the nostalgic references, like the first movie's sound effects being used as someone's ringtone. There's plenty of fanservice for those who loved the original.
Still, not a lot happens. The majority of the movie follows a forgettable protagonist trying to get a MacGuffin from one side of town to the other. It's kind of like a high-tech remake of 2012's Premium Rush.
If you're a fan of the first two movies, this is a great entry in the series. But it's still just as flawed as the other two, with more eye candy than substance.