Maybe this won't make sense. But I've been playing the Assassin's Creed series the last month or so to get ready for AC3 in about a week and a half, and I can't help but notice they have the same 6 or 7 people voicing all the roles. (Or so it seems) The performances themselves aren't half-bad, but I can't stop myself from saying "Oh, that's the same guy who voiced Malik in AC1," or "What's Cesare Borgia doing in Syria? I thought I killed him already."
Contrast it to something like The Simpsons and, well, do Apu, Superintendent Chalmers, and Cletus sound anything alike? They're all Hank Azaria.
I'm sure this can extend to other works that are in some way animated (Family Guy, hullo), but it's been on my mind lately playing AC. Does this ever bug you at all, when you can tell who's behind a voice?