Things suffer when a big name voices things most of the time. The big name actor is'nt good usually, the entire thing, even the characters appearance is focused round them sometimes.
It's a stupid thing to do.
One of the rare exceptions is Liam Neeson in Fallout 3. Great work, wasted on a moronic character. Most of the good ones are voice actors who gained fame and respect from being voice actors, not gimmicky big names.
I don't care who voices things, so long as they sound right! Pisses me off when they have some big name do a character, and they're crap, when a good voice actor would have been far, far better.