Remember the days when everyone and their pet iguana was raving about Arch Linux? You couldn't escape the ever-so-subtle "I use Arch BTW" remarks in every Linux forum. Well, move over, Arch, because NixOS is here to steal your thunder! Nowadays, it seems that you can't browse YouTube or read a blog ...
I've been on nix for only 2-3 days so take what I say with a grain of salt. I think it's pretty useful. Back in Arch/EOS, I always find ways to mess up the system (I switched to Nix because of a failed system update on EOS). On Nix, it's so easy to roll back and you don't even need to use the terminal.
sudo nixos-rebuild switch --upgrade
There are (afaik) 3 channels you can choose: stable, unstable, and small(?). I'm staying on stable for now. Package manager is slower than pacman, imo, and it's not as straightforward as Arch. Some programs (like kde connect) need to have service enabled in config.
Been using it for a few years now, it's freaking amazing.
My laptop died, recovery was: 1. rebuild my system from git 2. load the backup data. Took me about 20 minutes to prepare everything, went on with my day and when I got back to the laptop it was right as I needed it.
I need to target different Python version, with packages and everything, on different systems. Using nix I can a git version of a project to a Python environment, and it just works. Same with other languages.
Rollbacks are epic for experiments.
I can duplicate shared settings between computers, for example, I have a desktop PC and a laptop, both run the same DE, browser, email client, etc, all those goodies are defined from the same file. My server runs no DE, so its configuration file does not load the PC nix file.