I quite enjoy it!
Being able to rollback any change I make to the system, either package changes or system configuration, makes it completely unbreakable and provides great peace of mind. It means I can fully enjoy its rolling-release nature without worrying.
Having my entire system configuration declared in a single, robust programming language (Guile) across a small number of files makes it very easy to understand and just stick into source control to reproduce.
Being able to hack on it in a lisp (scheme) is the cherry on top, along with the great emacs integration. I would highly recommend it to any lisp/emacs/gnu enthusiasts.
I have never used nix or nixos. I liked their shared idea (functional, atomic, reproducible systems), and so when I looked at their differences they seemed to all be pros for guix:
The only bittersweet aspect of guix compared to nix was the foss only stuff, as I do need some proprietary drivers, but nonguix is so easy it hasn’t been a practical issue. And of course I am big advocate of free software so I like that guix is pushing that forward.
There’s also a theoretical issue that guix has less packages, but the standard channel + nonguix has had everyhing I use.