It is a fantastic init system/service supervisor. My problem with it is basically everything else. I think its developers see systemd as central to the entire system, basically the userspace counterpart to the kernel. I prefer the approach of 'dinit', but I understand why they designed it that way.

Due to this design they often have underspecified interaction between the different components, since the assumption is that everyone will use largely the same baseline systemd environment and as long as it works, who cares what it does underneath. If the different parts were more independent, they would be forced to develop a cleaner API contract between them.