My consistent experience is that Ubuntu is excellent for most purposes for "ordinary" users if you don't want to do anything unusual, including installing the latest versions of some software (Firefox and TeX Live among them). If you do, you may get lucky and be able to find instructions that will work the first time around; if not, possibly the second or third. But — and this is something I think about both Mac OS X and Windows — it really doesn't seem like it should be this hard. There are certain things I prefer about Ubuntu's software installation: Opening up a Terminal window and typing
sudo apt-get install [whatever]works surprisingly often and is even easier than the process of finding and installing new software in Mac OS X and (in my very limited experience) Windows. But why can't it always be easy?
In my work as de facto tech support where I work (the one-eyed man among the more-or-less blind) when I look at what I have to do to fix even some simple things, things that I do so commonly they've often become second-nature to me at this point, I realize that to ordinary users they're entirely unintuitive. Admittedly complexity is a price that must be paid for power, but does so much have to be that complex? Well, maybe someday; here we are in 2010 and I still don't have my jet pack, after all.