I'm not going to repeat what others are (correctly) saying about bad acting and too much CGI.
For me, it was the lack of Han Solo. Not that specific character, but someone like him. The original trilogy had 2-3 Jedi and Han was there as a no-magic rogue who spoke for the audience. "The Force huh? Psh, give me a good blaster any day over some hocus pocus magic".
Then in the prequels, EVERTYHING was The Force, and Jedi were EVERYWHERE. And not a single down to earth scoundrel in sight.