I love Fallout3, but I only play it on the 360, no show-stopping bugs in that, in fact I think any problems I've had are due to scratches on the disc.
Ohh there is one bug that annoys me, vault 87, the one that you get to by going through Little Lamplight - it won't register that I found Vault87 and I've been there half a dozen times and searched every nook and every cranny. So it means I can't have my 100% location achievement, I found everywhere else! - seems a bit cruddy that I spent the time finding them all, only to find it's impossible!.
I'm not sure why they did it like that - if you try and go to the main entrance of vault 87 you die from radiation, and if you get inside and find the main entrance, you open the big cog door and there's nothing on the other side!. They should have made the vault complete, so these problems can't happen - I see that as a major cop-out, fair enough, force the player to take a different route, but then if someone is cheating, if they have god mode on - what then?. I don't think they'll find an entrance, when really that should be an option, if only to let the play get inside, find the real entrance, go outside again, and die horribly from radiation. At least that way it might feel less disjointed. Little Lamplight is cool, and Vault87 is cool, so that's quite a big part of the game, it's where you meet Fawkes and get the GECK device - I just think it's a bit of a shame that the allowed such an obvious bug to sit there (I mean the cog door opening with nothing on the other side). Everyone is going to try and find the entrance, everyone will find the bug, nobody will unlock all locations. And even if they fixed the bug in a patch, it means I still have to go through Lamplight again.
Besides that it's an amazing game that I have to restrict to playing at the weekend, I start playing, get engrossed, and before I know it I have 3 hours before I need to go to work. I think the newest download looks the best so far, has a great Deliverance feel to it, maybe they should have replaced that old cow with the violin with a creepy, mutant hill billy with a banjo.
Anyhoo, I tell everyone I know who likes these games to buy it, the little niggles here and there, like the one I ranted for half an hour on, well they are little chinks in a massive game, if the game was to be 100% bug free then we'd still be waiting on it. Buy it now, and persevere, the game gets crazily addictive as soon as you have your own place and some interesting missions to do.