Clashing Sabers has an interesting essay about Anakin called The Plank In Your Eye:
Think about it. He starts as a slave and he ends as a slave. The whole journey in between is really trying to figure out where he fits into the galaxy. Is he a lover, a Jedi, or something else entirely? He never really figures out until he meets Luke, and realizes that his true purpose is found in his son (and hopefully his daughter, too, although we never get to see it). But to say that Anakin is without motivation is a fallacy.
The author also relates Anakin’s problems to some very serious personal issues.