Even during the best of times, George Lucas has never been known as an "actor's director." Watch some behind-the-scenes footage from the making of the original 'Star Wars' trilogy and you'll see the actors straining for a reaction or direction from the man. Spielberg he is not.
If you want verbal proof of Lucas' indifference (for lack of a better word) to the acting craft, 'Star Wars: Episode One - The Phantom Menace' star Terence Stamp ("Chancellor Valorum") is here to lay it out for you in no uncertain terms. George Lucas is boring.