The core issue with the prequels was that Lucas saw Natalie Portman in The Professional and decided he had to find a role for her (she was awesome in that movie by the way) and a couple years later saw Lloyd in something (I hope it wasn't Jingle all the way) and then decided he'd be the perfect child Anakin. He then tried to craft a storyline where a nine year old boy and a sixteen year old girl end up being soulmates.
Among the worst parts about the prequel trilogy was how limited a role Portman had (especially in the last two), considering her acting abilities. Competing with this was the storyline being little more than fill-ins around action scenes. Very little of Anakin's backstory, especially his turning to the dark side was fully developed. There were merely mentions here and there about how his separation from his mother, and later his fear of losing Padme allowed him to be seduced by Palpatine. The prequels were a missed opportunity.