Well liking something =/= it having good quality.
There is bad art. Cheap, uncreative and amateuristic. I see it everyday.
I loved the prequels, I basically know episode III by heart, but I do agree, that it's not that good movie-wise. It's not HORRIBLE as OP said, but it's not great. Still, I remeber the the CHAOS in theaters when it was released =)
I sort of agree, and when I think there's no such thing as bad art as if someone likes it, even though I hate it, I won't tell that person, "Its bad, and its a fact."
Cause that's the kind of attitude, I receive from most people who don't like the sequels.
And one of my main reasons why I liked the sequels was, Jedis, Jedis, Jedis.
I got hyped when Obi wan talked about the Jedi before they were extinct, and combine this with novels and comics, I was excited to see multiple Jedis on screen.