I thought at the very least it was a very competently made movie. Unlike many movies I've seen lately, the dialogue didn't make my eyes roll right out of their head nor did I hate the characters -- in fact I liked all of them. Even Clu was somewhat sympathetic,
this scene is awesome cause it shows how human he is. Heck I even loved that weird bald dude. A character that could have just been a bland stand-in is given life and character.
I never got the impression anything was underdeveloped, or made me question the plot, or made me hate the characters. That's the baseline for a "good" movie so I don't get why it's hated on.
I do have complaints; the biggest I can muster is that it didn't have enough emotional resonance, but it was still there. The black and white dream skipping stones, "Goodbye kiddo." They should have played that up. People harp on the solar sailor part but I thought it was pretty crucial. Oh and obviously young Bridges CG was bad but that's no reason to hate the movie.
But I love the movie overall.