Mac OS is BSD Unix with a major "simplification' layer on top of it. It is designed to be "idiot proof".
I am a Linux person (using it now). I bought an Macbook Air last month. I have powered it up about five times. Now I do not remember the login password. I'm not feeling motivated to bother with it.
I think it is pretty useless for the power user. It is perfect for the very causal user because it is 99.9% free of malware.
As for me, well, I will likley blow away mac OS, and install Linux on it.
Edit: Considering Apples recent blunders, I see no reason to invest anymore in it. For examples:
Honestly, most users had no idea we were using iMessage. I do not obsess over my phone enough to notice the blue vs green bubbles. Most people do not notice. What a blunder Apple! Why not let people opt-in to iMessage rather than leave it on by default? Anyway, I was lucky that I never had any trouble with iMessage, but millions of others were not so lucky.
With regard to iOS 8, now I wish I had my iPhone 5 with iOS 7 back. My iPhone 6+ is more problems than it is worth.
I suppose iMessage is enabled on my MacBook? I never took the time to find out.