I personally find it to be less immersive. I don't know why, I've never played any RPGs where the protagonist was badly voiced. I thought Hawke in DA2 had a kickass voice and that both Shepards in the ME games are moderately well done. But I never seem to like them more than the silent ones. I find myself far more attached to the Warden in DA:O than either.
EDIT: Ah, misspelled protagonist in the poll title. No matter.
EDIT: Ah, misspelled protagonist in the poll title. No matter.