I've never understood any of the arguments against it. I'm mostly a casual user but I find it quite usable. The most common argument I've seen against it is that it is bloated. But, I use a good deal of the components that people complain about.

systemd-boot is a nice little boot loader. it's much simpler to configure than grub, and does everything I need.

systemd-logind seems like a reasonable thing for the service manager to do. I like the per user service management.

systemd-journald I can understand people being annoyed that it stores stuff in binary, but again why wouldn't the thing your using to manage your services also manage their logging.

udev I don't have to interact with it too much (maybe thats good), but I do use it to automount a usb I use as a cryptographic key and it works just fine for that

systemd-timer again this is what I use over cron, maybe cron is better, but i'm already managing services through systemd

I don't understand people's belief that the system should be brought up and managed almost entirely by bash scripts. starting and stopping services when they are needed seems to me to be the same use case as startup and shutdown.