My initial reactions to the 3D cutscenes and the voices were the same as yours. Turns out that after the first chapter, there’s only one more 3D cutscene in the entire game. The rest of the cutscenes use the comic book style, which I think works very well. So I wouldn’t worry *too much* about that.
The voices did grow on me, but I can’t really say how long that took. Once of the good things about this game is that it has a very well written story, complete with character development, and the voices of Al and the narrator are in some ways setting the player up for how the characters (narrator included) change later on in the game.