Simply put, kid, Linux and Ubuntu IS a real linux, is worthwhile IF you have the time and energy to understand what is going on on your computer.
While I learned MS-DOS to do clerical work, I learned Windows, the MacOS, and X-Windows simultaneously when I went back to college, to do graphics and programming as well as writing term papers, and found myself switching between them on an almost hourly basis at several points in my career there. After I left I settled on Windows for a while, but found it so unstable and irksome, especially compared to what I was doing in a couple of UNIX accounts I would telnet to periodically that as the millenium changed, I bit the bullet and learned everything I didn't know about GNU Linux/UNIX (except I still can't sed worth a damn). Everything is faster, I can use older or less powerful computers to do what the people around me do, but at the same time, while I seldom install things any more by recompiling the programs (except for the Linux Kernel which I enjoy having the latest version of (the one I'm running now was released on November 2 -- one week ago) when something goes wrong I find myself in the position of preparing formal reports for the developers and knowing yes I am a guinea pig.
It's not that the GNU/Linux OS is so good. It's always been about trying out new things cheaply and both Gentoo and Debian, the distros I am currently most comfortable with, are rife with users who joke about how they are or are going to be broken this time (My sound card just stopped working on my Gentoo laptop. Yes it is the OS). It's that Windows especially is so bad, and while the Mac OS has improved markedly, it simply maintains its focus on presenting things graphically, with relative ease, while opening itself up to more traditional engineering tasks. It's not improved either, if by "improved" you mean "accommodates how we REALLY use computers better".
I won't talk about Ubuntu separate from Linux except to say -- as a trained artist I am WELL aware of where Jobs spends his money in his presentation graphics, and Mark Shuttleworth's (Mr. Ubuntu as it were) comments about how that OS SHOULD be competing on its own terms with the Mac OS show a refreshing ignorance of the structure and nature of the marketplace which Jobs is so comfortable in. There really are not a lot of people who are interested in wedding the serious engineering GNU Linux comes out of and the color spaces and other things which make for a good presentation -- and Jobs pays them HANDSOMELY while M$ has been trying to get their other employers to work exclusively on Window$ while it undercuts them with abominations like Silverlight.
In practical terms, it is still easier to call a commercial printer and have them print out something you cooked up on a Window$ system than a Linux system, but you can DO it with Linux, and with the Mac it's not just easier, the result may be better. On the other hand, my experience with other peoples (the library's) Vista computers (which are now XP again) has been that the overhead of the operating system and the introduction of new proprietary Micro$oft codecs and formats mean that while there was a period during the late nineties when Window$ was comparable to the Mac in terms of performance in graphics, those days are long gone and are becoming more, not less remote.
This is not to say I think the superior graphics makes the Mac a superior product: both Apple and M$ have decided what their consumer is and are very involved in TELLING us how to run our machines, but the more user-friendly versions of GNU/Linux are just imitations of what they are doing, and the REAL secret of Ubuntu's success seems to be not only does it make it easy to get started -- but it makes it easy to turn into a Developmental Environment. It CAN do what Window$ can do AND MORE, but only if you know how to tell it to.