From NV I like all the music. I think my main gripe with FO4 (same as with FO3) is the over-played "nuclear era!"-theme (made worse in FO4), while NV in comparison just has a nice, calm western-theme. Such as Johnny Guitar.
The sass-i-fied version of Why don't you do right always has me whistling along, like a dickhead
Isn't the menu theme of FO4 the same as FO3? It struck me as very familiar
The ambience I judge separately, since it's all Inon Zur ever since FO3 (with the exception of some resurrected FO1-2 tracks for NV), and they're all pretty decent.
Go to :45-ish of FO3 and compare to opening of FO4 (around :08), they are definitely using some of the same notes, but arranged differently, and with different "vibe". There clearly are new notes in FO4, but the "throw-back"-elements are definitely there