funny; I am using a linux desktop right now. not dead yet.
Linux desktop is an OS for people who are willing to invest time to get an utterly fantastic, fascinating experience. It doesn't suit modern instant-gratification culture, no, and yes, it takes experience and expertise to get the most out of it, but once you get there, it's bloody amazing.
I'd recommend having it as a small hobby as well as tool, so you can spend time learning and figuring things out and broadening your knowledge.
Disclaimer: Using Arch Linux with the i3 window manager. No, it's not for everyone, but I absolutely love it.
I also have a Mountain Lion MBP, but AFAICT, I will be leaving the Apple cart after it dies and I'll be 100% Linux.
I need it for work, and I wouldn't have it any other way.