Their only massive games are the Fallout and The Elder Scrolls series. But games like Hunted, Brink, Rage are nowhere near the size and variety that Fallout or TES and they are problematic games as well.
Pretty sure, like Tarfu said Bethesda didnt develop them.
We can only hope the patches are released soon after the game is released. A bunch of people who play the game for 72 hours straight on launch day will be violently typing complaints to Microsoft or whoever.
I'm not being terrified by the fact that there might be glitches in Skyrim, it's probably the most massive game that has been made and it won't be surprising if some glitches will appear here and there. Just hope there won't be any tech issue that will ruin the experience.