Nix is definitely missing a good intro that explains what to expect out of it. That leads to exaggerated comments about its difficulty being copy pasted in just

Nix is definitely missing a good intro that explains what to expect out of it. That leads to exaggerated comments about its difficulty being copy pasted in just about any related online discussion. But as for the surprise thing though, I think that has more to do with you (presumably) using the unstable branch. Any rolling release distro would cause similar problems. Also for people less familiar with Nix, Nix doesn't force read-only configuration files. Configuration frameworks based on Nix choose to do so most of the time because read-only ones significantly reduces deployment problems compared to read/write ones that can change under your feet any time.