I don't always agree with Daniel Miessler, especially when he lets his inner American get the better of him and turns into a raving gun loony, but when he's right (which is about 80% of the time) he's right:
Do you want to use your system as a transparent tool to accomplishing something, or do you want your system to be in the forefront — constantly requiring your attention because this feature isn’t working right, or that part just broke after an update? If the answer is the latter, I’ll just shut up, because that’s obviously perfectly legitimate. But if it’s the former I ask you to take another look at your OS choice on the desktop.
This is why I run OS X as my primary desktop OS (the Ubuntu I've just started toying with on a work laptop was precisely because I wanted something to work on - I've got other machines I can use to get work done when that machine is having it's inevitable downtime).
I fix linux machines all day at work (well, not so much in my current job - perhaps that's why I'm toying with linux on the desktop again). I don't want to waste half my day just getting my desktop to work, so that I can then get down and start doing real work. I don't want to have to spend hours after I get home fixing my laptop just so that I can get X working again and start browsing the web.
True, Ubuntu seems to be miles ahead of where it was last time I ran it as a desktop; but still, it's nowhere near as rock-solid as OS X is. True, there are some freedoms I sacrifice by choosing to run a system that's not as open as Ubuntu - but the tradeoff is that I get a system that just works, every time.