I wouldn't quite toss the FO franchise to Obsidian just yet. The game is good, very good, but buggy as hell. Granted, the engine could use an upgrade, I think that Obsidian needs to show more chops before they are handed the keys.
Again, Bethesda managed QA and set the release date. If you want to blame someone for the bugs Bethesda carries more liability than Obsidian does.
I myself would like to see Beth continue in developing the franchise. FO3 hooked me.
If they do I really hope they learn a thing or two about RPG mechanics and writing from Obsidian. I liked Fallout 3 quite a bit, but it was missing a lot of the aspects of NV I really enjoyed.
Pretty much, every and I mean every Obsidian game to ever come out was a buggy mess. Other than above average writing Obsidian doesn't really bring much to the table.
Really? I felt they fixed a lot of the character development/stat issues that FO3 had and introduced some better mechanics to the game. Anyway, I've played all of Obsidian's games, and outside of some companion bugs in NWN2 I didn't find them to be any more buggy than the average game. I feel like this is something the anti-Obsidian crowd likes to exaggerate, personally. I'm not a huge fan of their games. I thought NWN2 was just ok, KotOR 2 had the potential to be great, but Lucasarts changed things on them at the last minute, and Alpha Protocol was pretty cool and ambitious but felt like it was missing something. I do think NV is excellent, though. If anything I think Obsidian either needs more manpower or they need to work with publishers that will allow enough time for games to be finished before release.
This is really going to come down to Bethesda fans vs. non-Bethesda fans, though. I don't think most people are being very objective in these types of conversations. Believe it or not, I'm a Bethesda fan.
Anyway, look at this reviewer's review of Fallout 3. He liked it, so claiming that it's not valid because he's biased really isn't very fair.