I do like Mark Hamill a lot more as a voice actor than a regular live actor but I don't think it's fair because of his car accident. I heard he had to have his face redone surgically and this caused him have weaker muscle reaction in his face, which, for an actor, is a curse. I think considering what he had, a face that couldn't really express emotion too well, and a cheesy script in the Star Wars trilogy, he did a pretty good job. Of course, I've not seen too many Hamill films post-Star Wars, though there have been a few where he showed up.
For the record, I think Hamill is great in A New Hope. He makes you care for Luke the second you meet him because he portrays him as humanly as possible.
I seem to be a minority in that I prefer Luke to Han, at least in A New Hope.
But man are his VO's classic.