Well, that's not what I said (I was talking about Skyrim), but it is the same world as any other Fallout game, and they are pretty well-regarded.
The game has skill checks, choices & consequences, crafting, difficult combat, various ways to approach a situation... everything that made Fallout so popular can be found in Fallout 3. But people hate on it because "it's Oblivion with guns" (which is so far from the truth it hurts).
And then they like on New Vegas which had so many problems. To be sure, I love both games and yes, I love them for different things. Saying one is one of the best RPGs and the other a completely crappy one is beyond ridiculous, however.
Forget how well the C&C was done in Fallout 3 as it's been 6 years or so, but do recall the game world being rather dull creeping around the drab city with invisible walls or the tunnels teeming with zombies. That and the hubs seeming rather disconnected and the BoS and Enclave showing up somehow.
Anyway, to each his own.