- mediocre config files - they decided that config files are declarative, which could be good, but it pushed simple (and visible) logic in /etc/init.d/* files into more complicated logic encoded in binaries. The simplistic config files seem to be more simple for systemd to implement, but harder to understand, maintain and use.
- binary log files. everything has to go through systemd to access them.
- responsibility creep - systemd started taking over more functions, and it doesn't seem to stop. Will systemd turn into busybox, with simpler poorer implementations of every single thing in the system? dnsmasq is similar. The thing is, busybox and dnsmasq are cut down implementations for smaller system that are alternatives to their full-featured brethren. systemd takes over the core of a system.