I feel like Fallout New Vegas is 90% the same game as Fallout 3, and the 10% that's different isn't "that" much better. I also think that "the writing and quests are SOO GOOD OMG!(TM)" that people crow about is also probably a 90/10 split as well. Most of it is bog standard Bethesda-style quests and dialogue and the 10% that's "better" isn't nearly enough to elevate it to the extent people do. It's fine. It's good. I'd even say I love it. I just don't understand the whole "New Vegas is the only one worth playing" smug attitude when they're mostly the same game except one is blue/gray and the other one is yellow/brown.
There are considerable differences between the two games (in both directions, if that makes sense), but they're less obvious depending on your approach to the games and your eye for what they're doing distinct from one another.
This video is, IMO, far and away the most interesting and thoughtful Fallout retrospective on the internet right now:
View: https://www.youtube.com/watch?v=V7FLCg4KdyE
Mind you, it's 9 and a half fuckin hours, not exactly casual listening unless you've got a day to burn. That being said, it is timestamped, so you could just jump straight to the sections you'd prefer to hear.
Anyway, Noah (who enjoyed every mainline Fallout game to varying degrees for their own strengths and despite their weaknesses) is absolutely incredible at highlighting the differences between each game and the rest of the franchise. Each game enables a different range of possible experiences. There's a bit of cross-over sometimes - like, you can play 3 and New Vegas identically to one another and come away feeling as though they're 90% the same - but with this video, Noah does an excellent job of highlighting what makes each game so interesting and unique relative to one another. You (and everyone else in this thread) should check it out sometime, it's a very good watch.