To be honest, I'm finding the voiceovers in Dragon Age to be highly annoying. If I hear just a few more "Can I get you a ladder...so you can climb of my back!", which is not only repetitive, but also OOC, I'm going to have to turn the voices down. The problem with voices in general is that I'd rather imagine how my character sounds then have the game provide something that doesn't fit my perception of how my character should sound. Dragon Age at lest lets you select among a few options.
Really, what throws me with the Dragon Age approach more than anything is that you only hear your character about half of the time. He/she is totally silent during all of the dialogue segments, or really any time where it's going to be readily apparent that it's supposed to be your own character that's talking, and not someone else. For the first 20 hours or so of my game, I never knew if it was my character that was delivering those one-liners, or one of my party members. (Not so much because they weren't distinct enough, just simply because there had never been anything to establish in my perception that when I hear that voice, it's supposed to be taken as my character uttering those lines.)
(Personally, I've never been all that huge a fan of the "I'm talking now because you clicked on me," thing that pops up in games of that type. I don't need the character to tell me he's going to disarm a trap, walk over there, or attack a bad guy - because I've just told him to do that in the first place.)
Frankly, I figure you either have it so that your character has a voice 100% of the time, or not at all. ie, either go all Mass Effect-y and have all of the dialogue spoken out; or leave the main character silent. When you get right down to it, I don't have a very strong preference to either approach. The Mass Effect thing requires a lot more effort on the part of the design team; and it's one more thing that if it's not done really well, it's going to take away from the experience. On the other hand, I don't usually start out with a terribly clear picture of who my character is - I've never had a terribly strong opinion on what they should sound like in those sorts of games, for the spoken dialogue to contradict that conception.
And obviously, if you just have a "slient" protagonist, then there are no such problems. The vast majority of RPGs I've played have went with approach, for rather obvious reasons - it's not something I spend a lot of time pondering, so long as the game is setup in such a way that doesn't lead me to question why I can't hear my character speak.
The only time it ever throws me, or takes me out of the experience, is stuff like in the case of DA:O; where there's little to connect that occasional voice to your own character in the first place. It just pops up out of the blue at (seemingly) random occasions, and I only eventually am able to discern that it's supposed to be my own character saying those lines through process of elimination.
Back to topic - I'm not too worried about this in Fallout 4. I have a feeling that we'll be sticking with the silent type once again, here. And I don't really have that much of a problem with that, either. The only decent way I can think of having the PC do much actual voice-over in the game would be to go down the Mass Effect road, where you don't know exactly word-for-word what you're going to say. (Because otherwise, you're reading the lines, then hearing them spoken - and that just seems redundant.) And (though I think there's plenty of potential for improvement and refining with that approach) I enjoy that sort of dialogue system - I also don't think that it's so all-encompassingly awesome that every single game ever made from now on needs to do it that way, either.