I've had shutdown (for reboot) hang a few times after a systemd update, forcing me to cut the power. It's made me a bit paranoid, so I block the systemd package from having updates automatically installed, and every 6 months or so carefully manage update and reboot of each and every server ...
and while "all software has bugs" systemd really has the most annoying bugs (by virtue of trying to do everything core to the system) and always insists that they are features and we are backwards whiny geeks for complaining.
EDITs:
there's the classic case of the linux "debug" parameter: https://bugs.freedesktop.org/show_bug.cgi?id=76935
and the even more classic case of firmware loading events: https://lkml.org/lkml/2012/10/3/484
and while "all software has bugs" systemd really has the most annoying bugs (by virtue of trying to do everything core to the system) and always insists that they are features and we are backwards whiny geeks for complaining.