Edit: Oops, pressed the wrong button.

Diverging slightly from the current discussion, I find some common problems/mistakes among many prequel writers (myself included to some extent):

1) In ANH, Obi-Wan states that Anakin was "already an excellent pilot". Yet, I've seen prequel re-writers turn him into a farmer, or street urchin, or some such that does not click very well with Anakin being a pilot.

2) Making Anakin too special. We all know that Anakin has to be exceptionally talented, that's why Obi-Wan trains him. Yet, I've seen writers exaggerate his talents in ways that do not correspond very well with the tough requirements for becoming a Jedi established in the OT. Some have him already self-trained. I've even seen one writer have Anakin keep a spaceship from crashing, using the Force, as if he was already like Yoda. Less is more here, I think.

3) The Republic and the Jedi. The Jedi order are clearly officially sanctioned, from what Obi-Wan tells us. And yet, it doesn't seem like they would be the armed forces of the Republic, because the Republic is a democracy that probably wants to retain control over its own military, not hand it over to a strange sect. This relationship needs to be plausible in the storyline. I've seen too many writers who create something not very convincing.