A friend just mailed that he was one of the people who ran into the disk corruption problem in Leopard. That sucks.
I never even think of something like that happening with an OS upgrade. Complete disk corruption!? How does that happen? OS upgrades are just supposed to swap out files in your "System" or "Windows" folders, right?
In my estimation, an OS upgrade should be a slam dunk for Apple. They have complete control over the hardware they're shipping to, so they don't have to worry about crazy driver conflicts. Plus there just aren't that many apps in use for their OS -- especially the customized business apps that Windows-centric businesses develop -- so they can QA a lot more easily against those apps. Given the Mac demographic, I would guess that the top 50 or 100 apps installed on MacOS represent some massive percentage of the apps installed anywhere.
If Apple is back to the old days, where MacOS was a crashy, aesthetically pleasing OS that everyone tolerated just because it was better than Windows 3.1, that would really suck for them. MacOS X -- based on my once-beloved NeXTSTEP -- is supposed to be the OS that Windows aspires to be. If it can't do the basics, like, for example, not corrupt people's hard drives, then I think they're headed back to that old reputation.
By the way, this is the third major PR blunder by Apple this year (by my count). How many times are Mac fans going to give these guys a free pass until customers start taking their money elsewhere?