In fairness, I once thought the same thing, but then I stopped to think about it. Is it really the actors fault that his lines are ridiculous, poorly written, and emo? No. I am willing to bet he did the best he could with the material given to him.
The source of my hate for the prequels has probably already been listed here, but I will list them anyway.
1. Utter luck of substance. There is no reason to care about anything that is happening. No reason to connect to any of the poorly written characters.
2. Completely diverges from its predecessors, the original trilogy, in character traits. IE. "and he was the best star pilot in the galaxy" - Obi-wan referring to Anakin. What do the prequels show? A dumb kid with luck on his side, mediocre skill, and frequent rookie piloting mistakes.
3. The prequels try to cram about 4 stories into each moment of each movie. It's poor writing at best. It gets worse when you actually try to analyze any of the stories, which the movies don't let you do during the film, because it swaps between them too quickly. When you go back an look at them, though, it doesn't take much to realize none of them make sense.
4. Characters: I will start with the obligatory "Jar Jar should have never been created".
Beyond that, however, really watch the video somebody linked earlier, leading to the Red Letter Media reviews of the prequels. They have it dead on. Seriously stop to consider the characters, and try describing them to somebody who has never seen any of the SW movies. Don't list their profession or name, or who portrayed them. Just describe the characters. Start with, say, Han Solo. How would you describe him? Now try describing Qui-gon. Good luck.