10.6.1. hasn't been as buggy as some make out - the majority of the problems sit squarely on the shoulders of lazy developers who couldn't be figged adequately testing their software or following the guides that Apple provided.
While I agree that SL hasn't been that bad for me in terms of "bugginess", I do want to quibble about about the "lazy developers" comment.
I'm coming from a Unix background, mostly Solaris and I gotta say that I've been pretty spoiled by Sun's backward compatibility. It's relatively rare that a major OS version upgrade just plain breaks all kinds of things. Hell, I've run binaries compiled on 2.5.1 and run them on successfully on 10. In the Solaris world, the one issue I've run into with 32 versus 64 bit kernels and booting and whatnot has been the tun/tap driver for openvpn. Other than that, for the most part, I boot 64 bit and run whatever I need to.
Apple, OTOH, appears to have a culture of pretty significant changes without regard to backward compatibility. Mind you, I'm relatively new to OSX, having started with Tiger, but the upgrade from Tiger to Leopard, and Leopard to Snow Leopard has required significant time. Solaris, for instance, introduced SMF and the old rc scripts continue to work as usual while I've learned SMF and migrated to that.
I've had to update shell scripts, re-compile software, figure out new ways to get things I need running at boot time working, wait for developers to figure out their problems and get new versions of software. And so on....it's a real pain if you use your OS as extensively as I do.
Thank god I do not have to maintain OS X in a production server environment! As much as I use my macs as servers for my own purposes, I cannot imagine all the crap one has to go through to upgrade and worry about databases, application servers, etc.
I just spend 2 days with the developer of Bonjour Mounter helping him figure out an issue with a new version of his software. Thankfully, he was very quick to respond to my initial inquiries and I was able to run tests and provide him logs and crash reports so he could figure out what the problem was. Turned out, it was something Apple changed, and he's had to create and maintain 2 versions, one for 10.5, one for 10.6.
I love my macs, and I'm reasonably happy with what OS X does. However, purely from an a system admin's point of view, it's not the most advanced OS in the world. Both Solaris and AIX have some really kick-ass features. But it is pretty darn snazzy for a desktop OS. It's done a much better job of integrating Unix with a GUI than anything else out there. OTOH, launchd is a mess. SMF blows it away from day one.
But, IMO, they could do a lot more to make things easier on folks as they migrate to new versions. For the most part, I feel for a lot of developers.
Mind you, some of the larger companies have really dropped the ball on staying up with SL. And that's disappointing as they have a lot more resources than the smaller guys, and it's been the smaller guys who have been busting their butts keeping up.