I did enjoy both Fallout 3 and New Vegas. I know that surprised some of my fans, who wanted me to hate the games and rail against their design choices (which I have repeatedly pointed out were different than the ones I would have made), but there is no arguing that more people enjoy the modern versions of the franchise than the older ones.
If I were to compare the two games, I would say that Fallout New Vegas felt like it captured the humor and style of the Fallout universe better than Fallout 3, but I have to hand it to the FO3 designers for developing VATS, a cool twist on called shots for a real-time game. I also loved the set decoration FO3. There was so much destruction, yet obviously everything had been meticulously hand-placed. So much story was told entirely through art. I ended up naming these little art vignettes and creating side stories in my head about what had happened. There was "The Suicide", a dead guy in a bathtub with a shotgun, and I figured he just couldn't handle life after the bombs. There was "Eternal Love", a couple of skeletons in a bed in a hotel room, forever embracing each other. There was "My Last Mistake", the corpse in the temporary one-man fallout shelter which obviously didn't do its job of keeping out the heat and radiation. My favorite was "Desperate Gamble", where I found a feral ghoul in an underground shelter filled with lab supplies and lots of drugs... except for Rad-X. I imagined that a scientist found himself irradiated and desperately tried to synthesize some Rad-X to cure himself before he succumbed, but he was too slow. I did notice that whatever was left of his mind sure did seem to enjoy toilet plungers.
If I had to pick something I didn't like about FO3, I would pick its ending. I hated the ending. There, I said it. I didn't like the sudden problem with the purifier, and I especially didn't like the lack of real, meaningful multiple endings beyond what I chose in the final few minutes (FEV or not, me or Lyons, and that was it?). But the worst thing about the ending was there was no mention of the fate of places I had visited. In my head I had already imagined slides for Megaton, the Citadel, Rivet City, Underworld, GNR, the Enclave or the mysterious Commonwealth. But I got... pretty much nothing.
I liked FONV's ending much better. It had a nice set of slides at the end of the game. They covered everything I was wondering about. I went with Mr. House at the end... and that seemed a worse choice after the slides, but still OK. It led to a law-abiding but somewhat impersonal Vegas. I wish I didn't have to kill the BoS, but I want House to control the future, so I had to do it. It was a great morally ambiguous choice, and the decision made me pause. That's a sign of good design, right there.