Asklemmy

The reason I've seen is that Lucas's flaws were on display in the prequels since he had the kind of power to make decisions with little pushback, while production of the original trilogy shows that Lucas worked best with people around him to help refiine his vision.

Outside of Ian McDiarmid and Ewan McGregor, the acting is bland and sterile. Hayden Christensen had a far better idea that would lead to the fall of Skywalker without changing much of the films. Major sequences are far busier than anything which came before, making the sequences pretty but less resonant and hard to follow. The four separate storylines in the climax of I was too much, especially as most people were there for the best lightsaber duel ever. The camera work for talking scenes is shockingly basic for someone as talented as Lucas was with film.

I like the prequels well enough, but I can see why some don't like them.