I am watching episode III after watching I and II during the last days. I must say, after reading this thread that pointed it out more than I remembered, the acting is very average at best at some moments, it's actually embarrassing sometimes. Young Anakin in I is annoying, he sounds like he is reading and not acting, and although I know he had to be sure of himself, he sounds like an ass, not cute at all. Grown up Anakin in II is the worst actor of the main characters, his acting is very average. It's like along the prequel, every time Anakin has to play some sort of feeling, he presses a switch, and everything feels forced, from when he is angry to when he is declaring his love (in II, when he does to Padme, it feels so awkward, like "wtf would you do it so fast and at this moment, she's totally not gonna fall for that". If Natalie Portman was not there to save the show, it would have been a disaster on the acting side ! A few awkward moments too, like Jango Fett's kid (Boba Fett that we see in V) who answers to his father's line by a "aha!" laugh that feels so awkwardly acted. Like Star War's casting couldn't find a better young actor to play 2 lines and 3 laughs in the whole movie ? Also, in I, Qui Gon Jin is indeed characterless. At no point he has an aura or feels like an important character. He even dies an non remarquable way, I'm not surprised no one remembers him.
Oh and yeah, Jar Jar Binks is annoying as hell and just ruins I, and I hate the ending battle, what a clown joke ! I know Lucas was trying to catch kids with this, but I think what he did with the Ewoks was way cooler. They still look cute and their battle is entertaining, but the I ending battle doesn't make sense, not to mention it is totally useless because in the end the droids were deactivated (they lost anyway) from space.
I still enjoy a lot the aesthetics, I think those who did the best work overall are the designers, I love how they mix old and futuristic, the spacecraft designs are really subtle and I love the mix they did between 60s kitch old cars and all, and futuristic spaceships. I also like how every machine or weapon used in the prequel reminds you of the Empire machine designs in the original series. Even the personal spaceship ObiWan uses in II looks like a sized down empire destroyer ni the making. I still think they feel like a totally different movie than the original's, but still I think they did a great job. The look of Padme as a queen in I was a good call as well. I like how both evil characters (Sidious and a more subtle way Palpatine) show their hands out of their robe when they walk, it triggers in your head the use of the force the dark side way, like Palpatine as an emperor in IV/V/VI.
I love how the music themes announce the future and link with the original. For example I noticed the original's main theme only appears for the first time (it rarely does anyway) in II when Anakin is in Tatooine, which is where Luke is presented in the beginning of IV, with the same theme if I'm right. Of course you have the empire march theme at the end of II when you see for the first time the clone army being assembled but that didn't feel as subtle.
Now I'm gonna watch III which is to me the only really viable movie in the prequel for it focuses on what people really want to see in the whole thing, and has less useless moments.