This year I bought Fallout 3 (GOTY version) on a Steam sale, but as I played Fallout 1 & 2 only once, years ago, I decided to play them again before playing F3 (yeah I know they're different, made by different companies, etc).
I started the first Fallout thinking I wouldn't like it as much as when I first played it, that my memories were colored by nostalgia, and so on. The interface is a bit wonky at first (or after some years without playing), and the isometric perspective sometimes gets on your way (things behind walls for instance), but after getting used to these small things, the game shines. Very well written, excellent characterization, etc.
I'm almost finishing Fallout 2 now, which I'm liking even more than the first, despite the bugs. Maybe it's because I played F2 less when it originally came out, but right now I'm liking it more than F1.
I hope that when I finally get to play New Vegas its bugs will have been fixed. I still have to play Fallout 3 before I buy New Vegas, though.