Honestly, Three Dog was annoying as hell. I will agree with the poster that stated that Mr New Vegas could have a few more lines to say, but honestly... I prefer listening to him that Three Dog shouting in my ear all the damn time.
Also, the ambient music is from the original games, which by itself is pure win. I mean, I've actually caught myself with the radio off forever... only turning it on in situation where it adds a bit too much to the ambient (I don't like it in Vaults where ghouls will jump at you...)