2011 iMac 3.4GHz 10.7.4, updated without issue
For all I love about the Mac, the OS, compared to Windows, really seems like amateur hour way too often. If you disagree, make sure you're not mentally stuck in 95 and XP land.
In my XP years I certainly had my fair share of blue screens. However, in the two years I've been using Windows 7, with the same workflow as before (programming and graphics production), I had one crash, and that was because I accidentally knocked a PCIE card out of its slot. In the year I've been using OS X I've had to restart the Finder countless times, had Time Machine corruption on several occasions, and have to deal with "lazy" updating of the filesystem's "visual" state.
There are certainly things I like more about OS X, and that's why I'm still using it, but it really is a technically less sophisticated and more chaotic environment than Windows. Being technically less advanced isn't a negative, rather I can't get over that updates screw things up so often, especially given that Apple has way more control over the environment than MS does. Updates in Windows 7, which were much more frequent than for OS X, *never* disrupted the OS, and never even my most obscure 3rd party software utilities and apps.
I continue to use OS X because overall I like the feel of it more, and of course for the Apple ecosystem, but I do so with a constant background tension of whether or not it will remain stable.