Hmm yeah it probably helps to be able to program functionally (it's basically lambda calculus with lazy sets and a little bit of syntax sugar). NixOS has a little bit of a steeper learning curve. When understanding Nix itself and having a little bit dived into the the nixpkgs repo you'll quickly get a grip for it (and understand some of the IMHO quirky design decisions).

But then I feel it's only going to get better, as the system can be perfectly configured to your liking and it stays like that across different machines etc. I think the initial investment has paid off for me so far. It's really hackable and you can quickly try ideas without having to fear to break your system. Also something like nix flakes for good reproducible dependency management across different OS is really nice (at least if not much if any GUI is involved, then the different worlds (impure vs pure) sometimes clash together).