NixOS is the best operating system I absolutely cannot recommend to anyone - Anurag Singh
(www.xda-developers.com)
NixOS has some neat ideas but goes to the deep end implementing a near-perfect design of those ideas. If you need those ideas, it's really great.
I'm fantasizing about doing a lipstick-on-pig kind of a facsimile of NixOS on top of Arch Linux.