Another potential issue with voice acting is that you don't necessarily know what your character looks like or how they act (movement/animation-wise) in the game. It's much more difficult to get a voice 'right' when you're trying to mimic unknown mannerisms.

Well if audio is the quickest way to an enjoyable immersion, Skyrim's voices are decent, at best. Hearing the same actors play (seemingly) dozens of characters can break that immersion faster than anything. I'm new to TES, but never noticed such repetition in BG or NWN or DA or ME ... course, those games are much shorter than Skyrim. Shorter and sweeter.

I did like Senna's voice, the priestess of Dibella, and I was downright ready to commit advltery with Astrid ...

BG did have some great voice acting but Skyrim is not really bad. In fact there are some that are quite good.

Besides the lack of recognition the game has, I like Farengar's whole "Leave me alone with all your political nonsense" talk.
Wes Johnson did a great job in Skyrim as Sheogorath (once again) aaand Hermaeus Mora.
I liked Plummer and Von Sydow's voice acting. Cicero (Andrew Morris) is probably the most entertaining of all, at least for me.

When you tell someone "May you die with a sword in your hand"...the W in sword is supposed to be silent.