To me, a lot of the visual appeal of the original series was that everything was gritty and "dirty", giving the sense that people really did live in this universe and made it seem very...real. The past few movies have just been too clean and slick and lacked the same feel to it.
I do think that people are too harsh on the prequels in general. They aren't really bad movies by themselves, they just suck compared to the original trilogy.
I agree that the script for the first movie was pretty terrible. I like how they turned the whole Force mythos into Parasite Eve by saying microorganisms let Jedi use the Force. I've seen people say that the midichlorian crap was just some crazy theory Qui-Gon had that no one else really believed, which would be ok if they actually said something like that in the films.
I think the first movie would have benefitted a lot if they played up the whole Qui-Gon being deluded with his non-traditional theories on the Force thing, which is why he believes Anakin to be some sort of saviour rather than the antichrist. It would have made his character more tragic and interesting. That and not have the retarded Gungans or 15 minute long pod-racing scenes.
I guess the new movies just don't do the whole mythology justice. It's pretty telling when I'm looking forward more to the sequel to the Knights of the Old Republic video game much more than the new movie.
But I also agree that so many fans have become so jaded of the films, or have hopped onto the hate bandwagon to be cool that there's no way anything Lucas does won't get complained about anymore