Heh, that's pretty much what happened to me, only in reverse. When Fallout 3 first came out, I tried it but it was so different from the Fallout games I was used to that I couldn't really get into it. Then I returned to it a year or two later, knowing what to expect. I still don't think it's great, but playing it might've made it easier for me to "accept" New Vegas, which I think is probably the best Fallout game, combining the best aspects of 1, 2 and 3.