I played and loved FO 1 & 2. I was so disappointed by 3 that I never would have tried New Vegas if a friend hadn't bought it for me as a gift. New Vegas might be my favorite single player game.

It's unfinished. You can tell when and where they ran out of money. But the vision, atmosphere, characters, lore. It's just so fun to explore. I highly suggest you take the Wild Wasteland perk at start. It doesn't do a whole lot, but it's the little things you'll come across that'll make it feel like the first two games.