OS X is based on FreeBSD, FreeBSD being a modified version of berkley(I have a feeling I speeld that wrong) Unix. Technicly OS X is just a shell on top of a modified version of FreeBSD.
Now on if you should get one or not. Personally I would say no, but that is proably based on my anti-apple bias. I think its one of those situations where you either like apples or you hate them, personally I hate them, they are ugly (I dont want my computer to look like a **** desk lamp), they dont run alot of what I want to run, your stuck with apple-made hardware, and apple doesnt really listen to what their users say, so when they screw up your stuck with their screw up.
An example of this is the round mouse that shipped with the original Imac. It was a gigantic failure, there was no way to tell which direction the mouse was oriented by feel, so you would move it one direction and it would go in another. Despite numerous complaints about this they never did anything about it and never even admitted that it was a design flaw.
The only real good things that come with OS X are the things that it gets from being based on FreeBSD, and a better way to get these features is to get a PC and put FreeBSD,Unix,Linux, etc.. on it.
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Back in the day Windows user criticized Apple users because the Mac OS was a pure GUI with no command line interface behind it. Now Windows is a pure GUI, and OS X has a command line interface behind it. Guess what Windows users say now...
