It's not that UNIX is so great. It's that everything else is so much worse. When things suck bad enough, someone does something about it. (As it was with Multics... after all these years, people are still pushing more crap systems on us, forcing us to retreat to UNIX.) When you delve into this OS you break free from all of the crap and, if you stick with it, you can actually see that things can be made simple. Quite refreshing, I think.
Beware the complexifiers, people who want to make simple things complex. They are like the Snark. Lurking in every tree.
http://m.simson.net/ugh.pdf