I read negative reviews about this movie from people who claim it pales in comparison to the original. Frankly, I don't know what they are talking about. The special effects are incredible and reflect the progress made in CGI in the intervening twenty-eight years.
The music is well planned and adds immeasurably to the movie. My only complaint is that in the original release, it blotted out dialog and made it difficult to understand what was being said. Apparently that problem was addressed, because the versions I see now have the music toned down enough to make the dialog understandable. I'm sure the purists out there will complain about the changes, but it makes the dialog clear and adds to the movie, so who cares what they say!
I only have two negative comments.
1) I found the ultimate fate of Kevin Flynn and CLU to be depressing. The complete destruction of that entire magnificent world seemed excessive. Of course, they did have Sam download it to some kind of device leaving the door open for a sequel, where the grid is revived in all its glory.
2) I also thought the destruction of the End of the Line club with the deaths of Castor/Zuse and Gem unnecessary.
However, those two events do not negate the special effects, music, and angst that exists between Kevin and CLU which makes this movie a must see.