I would say the installation experience might be a bit more involved, but once it's installed it's much more worry-free for me. On every other distribution I've used (including Ubuntu and co), it's very easy to break the system completely. On Nix, it's almost impossible because you can always boot directly into the state before your update. Once you've set up your configuration, you can install it instantly on other machines by copying one file. On other distributions, you would have to re-install and configure everything by hand. Many of the tweaks for which you usually have to read Arch Wiki are also built into Nix, so you just have to write services.myService.myOption = foo; and you're done.

For the second point, if you've got a package that just builds with the usual ./configure, make, make install, here is all you need to get a nix package for it:

  { stdenv }:
  stdenv.mkDerivation {
    name = "my-package";
    src = ./.;
    buildInputs = [ ... whatever dependencies you need ...];
  }

And the standard build commands will be run automatically. The only thing that's kind of annoying is installing binary distributions of packages since they need to be patched to work on Nix, but it's not the end of the world. Also, nixpkgs is so universal that I very rarely find myself having to add a package that's not in it.