I like Zur's work in some games, but what they had him do for Fallout 3 was, IMO, horribly out of place. It was more like epic fantasy (more appropriate for TES games) than gritty post-apoc. It would have been cool to have something a little closer to the FO1/2 music, whether it was Mark Morgan composing it or not. It just fit the setting better.
the only thing really "epic fantasy" about FO3's soundtrack was the title theme and the battle themes. the actual ambient exploration tunes were about as subdued as you could get.
the music shouldn't just fit the setting, though - it should fit the game itself and what you spend most of your time doing in it. FO1/2's soundtracks were more gritty and grinding and tribal because the primary focus of the games was your interaction with these gruff, jaded individuals in a fairly tribal setting. FO3's emphasis was more on exploring ruins and seeing these remnants of humanity everywhere and as a result the soundtrack as a whole was a lot more depressing and quiet without really taking the forefront. the music tends to reflect the meat of the game - FO1/2's strong points were the writing, FO3's strong point was the atmosphere.
NV seems to be an even blend of the two - the bustling interaction and (admittedly sinful) enthusiasm of the Strip being offset by actually having to traverse the wastes and see not just the settlements that made it but the settlements that didn't - so its soundtrack will probably a blend of the two stylistically.
