Quite clearly I won't be the popular opinion, here, but I actually
prefer New Vegas to Fallout 3-and I never knew about the Fallout series, even, until the latter. And I played the latter first. So this has nothing to do with nostalgia or "purist" notions-as it seems some from both Fallout 3 and the earlier games may have. As another stated, I think it has to do with preference. Especially in the difference between whether a person likes a clear, stated direction with a set-up story with some especially dramatic(and least to some) scenes, and lots of little side activities or whether a person enjoys the state where they're given to their own devices and free to do almost everything they want, with crap loads of story-driven quests(not the more menial tasks) and a fairly open choice on to which direction they're going throughout the game.
For
me, I love a game with a good story, and one that takes somewhat complicated thought. More so, I
adored the hundreds(thousands?) of options in New Vegas and how I could have an impact, and that changing a character's abilities and "personality" actually changed the
story's experience and story's ending. I remember how in Fallout 3, I had to give the character 1's and 10s in its S.P.E.C.I.A.L. in a bunch of things to ever notice an effect, and the effect was only in gameplay-not so much in story. The character's are also far more in-depth; Hell, in Fallout 3 your companions were basically blankly thinking followers blindly acting as you wanted the moment you recruited them, in Fallout: New Vegas they have their own quest. When I can actually get to understand a character better and learn about them, I find it both fun-and, additionally, it's easier to care about them. I care far more about Veronica and Boone, and even Ed-E, than Faux.
In Fallout 3, you have a morally, completely black antagonist(pretty much)-President Eden, and a morally, completely white good guy(s)-James, among others. It ends up rather tacky with a number of plot holes, plot conveniences, and "fridge logic." Neither are given too much background, and all the other characters are even, depressingly, severely less so. In Fallout 3, the story's the same after the first time-with a few very,
very subtle differences, as you can't even let the Enclave win and
have to side with your father and the Brotherhood of Steel. In Fallout 3, you are far more restricted on the variety of a role you can play(the whole father and vault thing could have been great, if the story was better written, but ends up acting as more of a restriction to one's own, RP imagination-to some) due to the number of events you
must experience and have. In Fallout 3, RP aspects and gameplay factors are far more unbalanced-you can have a God-like character by the end of it just from leveling up.
In Fallout: New Vegas, you
can't do much in comparison to Fallout 3-
if you're talking about the little, random tasks that you can do forever and ever. Like finding books. However, if you're willing to change up your character and their actions, Fallout: New Vegas has, exponentially even, more content than Fallout 3 ever could due to its far more open and flexible story.
Not to say Fallout 3's completely crappy-I loved the concept, the exploration, and the reintroduction to the game series, but Fallout: New Vegas beats it without contest-with a more elaborate story and with characters who aren't just random, funny, and weird but actually fleshed out.
I will say that, although I don't really miss the characters due to the writing flaws of them, I miss the music-I don't like Fallout: New Vegas's radio quite as much. There's not much else I miss
extremely from the game, though I do appreciate my memories of it.
And, in response to some of the complaints, a
few of the things they took away-like metros-were because people complained about it so much. I believe Fallout: New Vegas was a good deal in part made as an attempt to please the fan base(and in any case that Bethesda/Obsidian at least listen
partially to their customers' complaints), though I'm growing more and more convinced that the fan base is broken. And as for things like how you sell to specific people for sometimes up to a 100%+ of an object's typical value, they might have done that to balance the game better. Another problem/complaint was how freakishly easy Fallout 3 got after a certain point. In part because you appeared to have 99% of the Capital Wasteland's wealth after that certain point and in part because you could be so overpowered and, as stated earlier, God-like. Which is probably also why the dart-gun went out(as much as I would
love that thing, once in a while, when I have to deal with those Deathclaws. Or, better yet, those frickin' Cazadors.)