NixOS is configured using the Nix package manager, allowing your system to be replicated and kept in sync across multiple machines. Great for keeping a laptop and desktop in sync.

Atomic non-destructive upgrades / rollback of a system upgrade / declarative reproducible system configuration / unprivileged installation of packages / transparent source or binary deployment.

Packages don't break after a NixOS upgrade as they are prone to with other distros (especially Arch).

You can start with a minimal environment and add packages and software to suit your needs as you go along.