I’ve ran NixOS on my last two machines. I like it more than the alternatives, but it isn’t without flaws. At this time, you must be sold on the idea of declarative configuration and willing to learn at least the basics of how Nix the language works.

It’s cool that you can Git pull and build an OS, but management of the project can be very slow. Using a ‘pull requests’ model majorly slows down progress; if you need to revise changes for a new package or package update, you will make the correction and get approval, even as a maintainer, but no one will come back around to merge it. With a patch-based model maintainers can waste less time by just making those few modification to the patch and getting updates upstreamed faster without the back-and-forth.

That said, it’s still something I’d recommend for someone with the experience and interest. There’s never been a system I was as confident with running patches and just updating the system myself for when stuff wasn’t working. But also, Guix is out there doing similar stuff and you must admire the free software goals even if it can sometimes be impractical (I just do not like the Scheme-based syntax).