One thing before I go on. Change does not equal progress. Things can and do change for the worse, and the topic being about Fallout 3, it's a very good example of both positive and negative changes depending on what your opinion is.
So, it got a new engine, new gameplay. As was rumbling about when F3 was released, a lot of people had a problem with VATS etc. and how it wasn't Fallout any more. And, by and large I think those people were wrong. The Fallout series as a whole was never great because of it's turn-based isometric hex system. The gameplay frankly, could have been done in the style of the semi-real time DnD isometrics and they still would have been good games.
Neither were the graphics all so great either in the old Fallouts. The aesthetics though, spot on. Fallout 3 is, imo, a run down trailer park in comparison to the Wasteland of Fallout 1 and 2.
Everything else, F3 fumbles on, atrocious dialogue, that while not as bad as Oblivion's, is frequently cringe worthy, not least of all when combined with the stiff delivery for the nth time and in the same voice. What is the point of claiming that all your NPC's are 'fully voiced' if all that boils down to is having a tiny pool of voice actors reading off pre-set lines for non-important NPC's who have nothing useful, nor interesting for that matter to say?
I won't go into the ending, (it sucked hard by the way), but why exactly does what is -supposed- to account for the 'main quest' end up feeling like just another thing you've got to do? Maybe it's just me...but in an RPG, the main plot is supposed to be epic, it's supposed to be gripping. Everything else is a sidequest. Some more interesting than others, but always tertiary to the main plot. Why here then does -everything- you do feel so insignificant?
I actually like Fallout 3 for what it was. But, they could have called it Post-Nuclear Adventure land removed all references to the Fallout series and it probably would still be the same, maybe even better without either the hype nor the name to live up to. But it is hardly a prime example of a Fallout game. IMO. Of course.