I gave it a go twice and i just couldn't stick to using it.
So many annoying little problems in general that i gave up. I configured system in the end but it was still annoying. I even had conflicts with some pkgs like Smile emoji picker and Gearlever, ok you can say: why do you need that? but lets say i do. And i got a conflict and couldn't install them together. I thought the whole point of nix is to have independent pkgs but i get in practice a conflict which now i have to figure out how to solve and there is no info online.
There are many bugs and bad abstractions. I can use nix for local dev (devshells) though.
With Ansible i get repeatable setup of my whole system. I can setup and install every program, configure it (dotfiles), setup services automatically and users and i have vault to easily encrypt secrets end embed them or template things out which is much nicer than using nix. I run a playbook and set everything up in 15 mins and the most "annoying" thing i have to do is basically log into few websites that i use daily.