Well, some popular reviewers are rubbishing the prequels when it's clear that they haven't actually even seen them!
The prequels actually all got fair reviews at the time, and they were financially very successful. There's no real objective basis for the internet geeks to rubbish them.
My personal view is that the first two prequels 'Phantom Menace' and 'Attack of the Clones' were average, mildly entertaining movies, and the third one 'Revenge of the Sith' was pretty good. I mean RotS has got some great light saber fights in there.
Here's a link to another fav. fight of mine, Mace Windu vs. Palpatine. Palpatine was a genuinely scary villain. Damn good stuff!