It was a big shift from isometric, partially turn-based strategy-RPG hybrid in Fallout and Fallout 2 to first/third person shooter/RPG hybrid. You say Fallout 3 is very easy, a cakewalk etc etc and that Fallout 2 is brutal, well to me it's completely the opposite.
Fallout 2 did require some strategy but it flowed naturally when I played it and it never seemed to be a very difficult game, unless you wandered into a bad area of course.
As I am slowly playing Fallout 3 it is absolutely confounding to me, I keep wanting to revert back to certain habits I formed while playing Morrowwind/Oblivion. I get lost easily while looking around and it's taking me awhile to get used to the gun combat because I've been playing Borderlands recently as well.
It's awesome that you liked 3 enough to go back and check out 2, and it's funny reading reactions to the transition.
It's almost like if someone played FFXII and was all jazzed so you'd sit them down and make them play through FFVII..