Didn't like FO:NV too much, I think it was the world design itself that didnt interest me that much, it's not Obsidian's strong side (same can be said about KOTOR2 where KOTOR1 had a much more interesting world design).
I liked the different factions, that was done really well, but the rest was a kind of a "meh", including the story, while good it dragged on, i couldnt wait to be over with it. Didnt even play any of the DLC's that i had installed. New Vegas in particular was very sloppy and dull. Sometimes when i think "hmm, maybe i should replay it" and then i remember New Vegas…
Characters and story isnt Bethesda's thing, but they are the least important aspects in an open-world RPG imo, they do most other things really well and i'm enjoying Skyrim, so far, more than FO:NV. I should say i played FO:NV heavily modded including those overhauls for New Vegas.
Edit: "didn't like it too much", well at least i finished it, unlike 99% of all games i start playing.. so saying i "didnt like it" might be over exaggerating it...