Lucas is great at world building, knowing what he wants things to look like, and cinema photography. He has a good style for how to get things shot on screen and a nice selection of how to get to the next scene.
He is not very good at directing people to show emotions nor in writing convincing dialogue. Nor is he that great at editing. His ex-wife was much better at editing.
His hand can be seen in the Clone Wars, and that did well since he wasn't directing or writing. He was giving ideas, and he's good at that.