I have to concur on both notes. Hamill is both perfect as Muska and arguably the real star of the show. And yes, it's amusing that Hamill and Muska resemble each other. One suspects that if Miyazaki was casting this movie in English (which he really didn't), Hamill would be his first choice. Although seriously, I enjoyed the dub... a lot. It's not perfect (and yes, there are SOME additional lines I could've done without), but it's still a lot of fun and hardly does any damage.
Epicness, muska is quite the character