NetworkManager is still popularly referred to as "NetworkMangler", and for good reason. I had serious problems with NetworkMangler on two completely different distributions over a period of two years. I finally solved the NetworkMangler issues by switching to Wicd; its interface is crude and ugly, but it damn well works. I haven't had to restart my laptop to get a working network connection since.

If NetworkManager is an example of how great systemd can be, then I just became vehemently opposed to it.