Currently very basic gnome-shell launches on my laptop. Quite some
services won't start yet, most notable is gnome-control-center.
GTK3 apps still don't have theming applied and for example launching
chromium results in horrible red windows.
Gnome doesn't work at least since I started using NixOS half a year
ago, let's not give wrong impressions to newcomers. Packaging gnome3
is still something on horizon.
That is, you can say
security.pam.services.sshd = { options... };
instead of
security.pam.services = [ { name = "sshd"; options... } ];
making it easier to override PAM settings from other modules.