I asked my wife about her opinions of the OT and the PT. We only watched all 6 movies within the past 1.5-2 years, so her opinion is very different than, say, someone like a lot of GAF who went to the opening showings of the PT.
My wife had a very good point (and one that I agree with). The PT movies aren't great, but they give a good picture of what happened before the OT. So even if the acting and dialog are hot garbage in a lot of spots (see ROTS), the story the PT tells (the big picture story, not the little vignettes) were good building blocks for the OT and beyond.
And I don't think she's wrong. Anakin couldn't have been written to be more of a creepy turd of human being, but it's good to see how he went from a little kid to a power hungry maniac willing to do anything (like kill children) to get the power he felt he deserved. Sure, you can read books or articles to get that info, but the movies provide a different way of feeding the interested parties that information.
So no - I don't think ROTS is one of the "good" SW movies, but I don't think it's nearly as terrible as die hard fans tend to think it is. Newer generation Star Wars fans seem to enjoy the PT and the OT just fine for different reasons.