I have to say I was a huge Star Wars fan and I have just grown out of it. Every time I think of Obi Wan in the new movies, he reminds more of a dull professor than the Obi Wan from the old movies. And this was the main hero of the films, so that sucks.
If you think about it, what really killed the prequels was Obi Wan. He was OK, and that wasn't enough. I think we could have all put up Jar Jar etc, had we had a charismatic Obi Wan. The fact that he was so dull, made the prequels feel more like weird political films than fantasy films.
The original trilogy had not one, but two likable heroes. Han Solo and Luke. Both were charismatic and could carry the films.
The prequels had not one character who could carry the burden. Ewan McGregor was a real miscast. A more magnetic actor, and we'd be talking about the prequels in a better light.
The third prequel was better than the first two though. I liked the first prequel a bit. The child actor was fun in his own way.