I enjoyed all three prequels.
First of all, I thought the DVD cut of Episode I was much, much better. Sure, there is wooden acting, but the story of all of the prequels is great. There was some cringeworthy moments (now THIS is podracing, Jar Jar) but overall Episode I was entirely decent.
Episode II wasn't as good. I'm not going to argue with the fact that Lucas can't direct love sequences or write them. Then again, the OVERALL story still shines, and I don't let love sequences ruin the entire story for me. The action sequences again were great, and I enjoyed the film.
Episode III was, for me, on par with the originals. To say it is the worst of the prequels is absurd IMO. McDiarmid hits a fucking home run with his performance with Palpatine. Hayden Christiansen does a better job. The only painful part of the entire film is most definitely Natalie Portman. There was less love bullshit, which left more room for yet another great overall story. The lightsaber battles were well choreographed, the score is by far the best out of all the prequels... frankly you have to be massively anal in order to say Episode III is the worst. I really can't see that much wrong with the film besides Portman.
The first two were flawed, but for me they still pulled it off. I can understand how and why people can bash the prequels as well, but for me, Episode III is great, and it's my favorite prequel by far. It's the only one I saw more than once in theaters, and it's the only one I can truly call great.
The other two prequels I would probably give 6/10s, Episode III got an 8/10