This is simply the best distribution at the present time. It is not perfect yet, due to its youth, but the ease of use on the user side and the great reproducibility from the developper's side make for a versatile distro, working well on both server and desktop.
NixOS and guixSD both have the revolutionary reproducible packaging system, which allows for rollback of app installs among other cool things. In other distros, you could try to achieve that with ZFS or BTRfs & snapper , but good luck with that (it may not work for you).
Arya Distro from India (see below review) has much simpler install scripts and next to no packaging.
Reproducible builds sure are the way of the future -- combine that with KDE power, and your left with no alternative Linux but NixOS ! Downside is that ARCH has more packages and more GUI than nixOS.
The capabilities of NixOS for controlling the state of your system are breathtaking. For example:
* The configuration of your entire system is described in one, compact file and it can be reproduced at will on any other machine from just this one file. No more editing a dozen different configuration file formats in /etc!
* You can roll back to any previous state of your system (modulo garbage collection) without having to use a particular filesystem such as ZFS.
* Packages will continue to work indefinitely regardless of updates to the rest of the system, because they reference the exact versions of all the dependencies they were built against.
Packages don't exist for some obscure or unusual things (although it's very easy to create them yourself).
Vendor-supplied binaries (debs and rpms) don't work out of the box, although there are tools for wrapping them as NixOS packages.