On the contrary, I never had troubles with voice acting, I don't actually care if the same actor voices entire race if that provides more dialogue.
But on topic... first thing I felt about Oblivion was nothing special. I started to really appreciate the game much later, probably because I was used only to old-school RPGs before and what bothered me the most was 3rd person, I was used to 'view from above' games like Baldur's gate, Commandos et cetera...