I'm liking it too.
Some of the mouse response feels a bit sluggish, which combined with slightly hyper enemies means FPS combat feels kinda rough, but with VATS there, it hasn't been a huge problem (is anyone else spending a TON of combat time in VATS?)
It's also the first RPG in forever who's alignment system actually recognizes that walking into people's houses and looking all their stuff isn't really a nice thing to do.
I will say though, that some of the animations, especially of your character in the third person view, suck donkey ass. The fact that both the terrain and the characters look so good just make it that much more obvious that your character model floats along with next to no connection to the terrain. Though the solution to that though is to stick to FPS mode.
The combat is doing it for me in ways I hadn't expected though. It remained fun even after trying to clear the Superduper Mart for the third or fourth time trying to get it right, and that's something that normally kills games for me. Quick painless quicksaves/loads helps a lot. Loading screens are pretty minimal as these things go.
My only big disappointment though, is something Wired's Game|Life review mentioned and I can't shake now that I see it: It's just not funny. Which on the one hand makes sense (it's the end of the world after all), but the old Fallouts had a balance between the Nuclear Apocalypse, and a sense of the absurd. I just can't see, say, some of the random encounters from the original games in this one. Even the opening dialogue seemed a bit overwrought, and maybe that's an inevitable side effect of having the world more revealed now than the first game, or that this isn't the old dev team, but it's still present.
That complaint said, my first impression is that it's still by far one of the best action/rpgs to come along in ages. Even if it's not Fallout or Fallout 2, I totally don't regret shelling out for the game or making time in my schedule for it.