Systemd's primary selling point is that it has already convinced distros to use it.
It inserts bizarre delays.
It makes debugging harder.
It makes logging harder.
The documentation stinks.
It infects other systems (libvirtd, GNOME) and convinces them that SystemD is a necessary dependency.
In short: SystemD doesn't play well with others. It is not a good citizen.
Anything to do with systemd logging is a goddamn nightmare though. It loves to tell you that a service has failed to start, but doesn't try to do anything like show you stderr from the process that might help debug.
It does, actually.
sudo systemctl status the-service
sudo journactl -u the-service
> It makes logging harder.
journalctl -u or tail your daemon's log file
> The documentation stinks.
It's actually pretty decent, and once you dig through it a lot of the unit file properties are genuinely useful and solve real problems that shell scripts can't deal with.
> It inserts bizarre delays.
Like what? Nowadays all distros boot pretty fast with it.
journalctl is a terrible interface.
As for delays: you've never seen "waiting for [thing]... 5 min 30s" before? You're lucky.