[phunehehe0]

> Other than integration with the rest of the Nix/NixOS ecosystem

Nix/NixOS is the big deal actually. NixOps is just icing on the cake. A NixOS installation is configured by building/copying over a system profile, and then activating it.

With just NixOS, you edit a configuration file on the server, then run a command that will build a system profile from that configuration and activate it.

With NixOps, you have configuration files on your workstation, and run commands to build the system profiles, copy it to the servers, and activate them. Of course you can do all of this without NixOps. It just makes certain things easier.

Puppet and others can do all of this, too. However state transition tend to be the weakest link (e.g. tell Puppet to provision a brand new server vs one that has run some other stuff, how sure are you that the resulting systems are the same?). Nix/NixOS takes care of that (most of the time anyway -- there are still things like data migrations that applications have to take care of).