I've used NixOS as the only OS on my laptop for around three years at this point. Installing it has felt sort of like a curse: on the one hand, it's so clearly the only operating system that actually gets how package management should be done. After using it, I can't go back to anything else. On the other hand, it's extremely complicated constantly changing software that requires configuration with the second-worst homegrown config programming language I've ever used1.
