Played them all at their time. Judging by myself, I'd expect this mostly from gamers that are now in their mid to late 20's. When Fallout 1 was released I was a bit too young to be able to appreciate it fully (I was 14 or something), and it was a very special era of gaming, where you could buy The Dig one month, Pandora Directive the next, Diablo the following and Fallout right after that, so I was a bit overloaded on quality (yes, it can happen).
But I distinctly remember being on high school when I got Fallout 2 and it completely blew me away, I was playing it at the same time as my best friend and we finished it 4 times each trying to impress each other with little secrets that we've found and with our beefed up characters (we had no internet of course). I've finished it another 5 times at least since then, and today consider it one of my top 3 best games ever, for reasons that have been mentioned hundreds of times and need not be mentioned again.
As for Fallout 3, I've finished it 3 times on consoles and all playthroughs were quite different, which, if anything, shows a spectacular game. Haven't played the DLC's yet, waiting for the PS3 GOTY edition. It was much more restrictive and less imaginative in its settings than the 2 previous games, but the world came to life in a much more immediate and immersive way. My opinion is that it is a game made by true Fallout fanboys (in the best sense of the word), they did a good job, I enjoyed it a lot and can't wait to see them go even further with the series in the future.