I didn't finish the first Fallout, skipped the second, played the ever-loving hell out of F3 and FNV and am loving F4.
New Vegas is my favorite Fallout game. I realize that sounds crazy to some of you but it's true. It's a complimentary game to F3; You've got free-roaming with a bit of RPG story in F3, you've got RPG story with a touch of free-roaming in FNV. I've gone on and on defending New Vegas in other threads so spare me from doing it again. But if Beth asked former Fallout developers (doesn't need to be Obsidian) to develop another game I'll definitely play it.
Best of both worlds.