I hear this every time, but from my experience Leopard has been rock solid. One could say that the fact that there are 11 updates to 10.4 show how premature and low quality that release was, but it's just that every OS needs updating. They're all "buggy". Software isn't finished, it's abandoned!
Leopard added more new features and more new functionality than any previous .1 upgrade. Time machine, loads of new mail functions, spaces, quicklook, core animation, new desktop UI, stacks the list goes on... Snow Leopard looks to add a lot under the hood; Open CL, Core Text, Grand Central, new Quicktime framework as well as improvements on the implementation of many of Leopards novelties. The functionality in OSX is extreme and elegant, when Windows is still trying to get the basics right and LINUX is little more than a joke (although unbuntu is getting there). I, for one, am thankful for such an amazing OS in comparison to the competition.
As a long time NeXT/Apple alum, to mock Linux makes you a joke. The two most capable systems are OS X and Linux, but in matters of Consumer space, Linux is definitely behind the curve. More specifically, the Desktop Environments for both GNOME and KDE are developer specific driven, not consumer specific driven.
As a matter of development, OS X Cocoa is a pleasure. Linux has GNUstep but with very little interest in ObjC by the Linux community it's no where near the level it should be, after 15 years.
Linux embraces two camps: C with GTK/GNOME and C++ with Qt/KDE.
OS X has the benefit of all three.
Windows has the legacy of business apps, games and infrastructure of corporate costs making it hard to break from them.
Windows has had it's day in the sun. It doesn't mean it won't continue to be the dominant player for the next decade. It'll just see that dominance erode more rapidly than the last decade.
By 2015 they should lose an additional 15% of the market share.
Apple has to shore some critical hardware gaps on their pre-existing systems.
For the high end industrial needs they have to add more full length x16 slots to show a superior platform for OpenGL, OpenCL and GrandCentral, all which make for attractive bargaining chips to heavy industry looking to leave Windows and already have moved to Linux.
Device Driver options need to expand. Apple needs to fill out ATi and Nvidia's GPU offerings for OS X hardware thus making it more affordable for consumers to move to OS X hardware.
The embedded Systems markets are wide-open. With PA-Semi and ARM the sky is the limit on which markets they want to redefine.
Starting with the Smart Grid Markets and being the platform for handheld/embedded console systems that interface with heavy industry power systems would be a start, but I'm getting way beyond Apple's focus.
I'd start with getting Apple to partner with DirectTV and providing the consumer with future AppleTV/DVR systems you subsidize while upgrading to an all HD 1080TV package.