I've never played it, so I'm curious...
Does it fail because it's not a "true" Fallout, or does it also fail as a FPS?
It's a very mediocre game, but not the worst game ever or anything. It still has solid art direction (despite shit engine), it has a great sense of open world exploration with tons of stuff to find, despite balance issues the character system actually is not that bad, etc. As a Fallout game and a pure RPG it is not so great, but as Elder Scrolls with guns it's hardly unplayable. New Vegas was far better in almost any way but I don't think that really diminishes the fact that Fallout 3 did do some stuff well, especially as there weren't really any other games to compare it to at the time other than the Elder Scrolls series. If it wasn't called Fallout, I think a lot of people would have just said "oh, cool post-apoc shooter-RPG, 7/10" because there wouldn't be the same expectations for it.
Pretty much this.
Honestly, I can get past the crashes and bugs (mods help with the latter), character imbalances, lack of challenge, VATS (which is easily avoided), so on and so forth, but IMO, the game deserves all the scorn it gets for two reasons:
1. Its not Fallout. Not even close. Neither in flavour, nor in gameplay is this game a Fallout sequel.
2. The writing and voice acting. Jesus "The Toolman" Christ, could they possibly have made this game any more retarded and lulzy? I mean, really, you're going to have a relatively small handful of actors voice a game of hundreds of NPCs, and give them no direction whatsoever? Every NPC voiced by a given actor is virtually the same across the board, in terms of inflection and tone. Weak. And annoying. And holy shit, the writing...wow. I'm not looking for a literary masterwork, but fuck-me-sideways, Bethesda is rolling in dough, they can afford to hire somebody to flesh out a quasi-non-retarded setting, and write some believable dialogue; they have no excuse. Its like they felt they needed to one-up Fallout 2 on the disbelief scale.
"Ooh, I've got an idea, lets have a major town built around an active nuclear warhead! Oh, and lets shoe-horn super mutants and the Brotherhood of Steel! Hm...oh, dig this: a DLC on a spaceship! Dualing comic-book characters! Portable nuclear weapons! STEEL BE WITH YOUPOAHDSGOIUHSADIFUSHGDKUSDHFKSDFFUCKFUCKFUCK"
Mods can undo a lot of Bethesda's poor design decisions, but they can't (or at least,
don't; its not practical) fix shitty writing and redundant voice acting.
Speaking of Bethesderp, how does Skyrim compare to Oblivious/Fakeout 3 in terms of writing and voice acting? I'm holding out till the Ultimate Game of the Eon edition drops.