The ideas behind Nix/Guix are really interesting and a major improvement from traditional packagement solutions, and personally I much prefer using Scheme than a Haskell-derived DSL to configure my environment and operating system.
The problem is a political one: NixOS ships with current Linux standard technologies such as systemd, while this Guix-based OS uses this GNU dmd project I've never heard of until now, but I have no doubts its features and maturity is a fraction of systemd's (whatever is your opinion on systemd).
All for the sake of the free software radicalism. I love GNU and FSF and everything, but as a Linux user and administrator I'd really like we settle on something and build from there.
I may be mistaken, and open to criticism.