I tried NixOS out for a while on my laptop. I loved the idea of an immutable system with all the config in one place. The implementation, though, was really a terrible user experience. I got past the weird config language, made a few contributions to Nixpkgs to get the packages I wanted, etc. The deal-breaker for me was the inability to run third-party binaries due to the departure from standard directory structure. After all the frustrations with NixOS, I was motivated to go to the opposite extreme so I could stop spending time maintaining my system and focus instead on the tasks that I wanted to use my system for. I've been [mostly] happily running Ubuntu LTS releases ever since.