Same here as Ixyroth and shihonage.
I have to admit that I caved in and bought Fallout 3. Had to see for myself. I was rather disappointed in it for a number of reasons, primarily the main quest and how lifeless (as in Oblivion) the world is. The consequences for decisions are almost always instantaneous and self-contained, not to mention awkward and empty.
I yelled at my screen more than once when I was running around the citadel. What the fuck has Bethesda done to the BoS? Oh my god. "Steel be with you." "In the name of Elder Lyons!" Two BoS knights even had a conversation about whether or not a battlecry sounded gallant enough. The ending of the main quest was just as bad.
My complaints about the gameplay mechanics mirror many of those that have been said before, so I'll spare that.
It's not all bad, though. The game itself is okay. I could have enjoyed it if it weren't for the fact that the canon of the series is being forced to dance in front of me like some sort of gutted-corpse-turned-marionette. Bethesda took the "50's" thing too far. I don't think they quite understood what retro-future is. In any other game world, I probably could have enjoyed it.
All that said, Vault 112 was a blast, but only about as fun as (and extremely reminiscent of) Oblivion's quest for the Dark Brotherhood where you kill the treasure-hunting people in the locked manor.
As for Dead Space, I enjoyed it more than Fallout 3. Quite a bit more, actually. The mouse movement issue is fixed quite easily by turning off VSync. The camera, well, I personally had no issue with. The controls were my biggest issue. The PC was an afterthought, and it shows with the CTS-inducing bullshit you have to do on your keyboard to accomplish most things.
EDIT: I wanted to expand a little on the consequence bit. It's almost patronizing the way the game rewards you. High enough karma and children will say "I feel safer knowing that you're around." Occasionally a settler will run up to you and give you a random item, telling you that you're an inspiration to all. Gee, thanks for the bottle of dirty water. Bitch.