One contrasting feature is parametrized services: several similar processes (like agetty) can be controlled by one service directory; I find it neat.
Another difference is the ability to initiate reboot or shutdown as an action of the same binary (nitroctl).
Also, it's a single binary; runit has several.
Then I left Linux for about 5 years and, by the time I got back, Systemd had taken over. I heard a few bad things about it, but eventually learned to recognise that so many of those arguments were in such bad faith that I don't even know what the real ones are any more. Currently I run a couple of services on Pi Zeros streaming camera and temperature data from the vivarium of our bearded dragon, and it was so very easy to set them up using systemd. And I could use it to run emacsd on my main OpenSuse desktop. And a google-drive Fuse solution on my work laptop. "having something standard is good, actually", I guess.
On the other hand, systemd replaces Unix (sort of like Hurd, but differently). It grabs system init, logging, authentication, DNS, session management, cron, daemon monitoring, socket activation, running containers, etc. In an ideal Red Hat world, I suppose, a bare-metal box should contain a kernel, systemd, podman, IP tools, and maybe sshd and busybox. This is a very anti-Unix, mainframe-like approach, but for a big consulting firm, like Red Hat / IBM, it is very attractive.
DNS: Can you from memory recite how name lookups work on Linux? Ever had t otrack down problems with non-standard setups? `resolvectl` is not perfect, but it does let you control all of this stuff in one place, and with a nice, orderly view of what does what.
Init system: ever written the old sysV ones from scratch? Sure they're just shell script, but did you remember to make yours re-entrant? What about forking or master-slave processes? Hope you got your pid checking code just right...
Containers: Docker is quite robust nowadays but it's not like it follows the 'UNIX philosophy' either. And systemd/nspawn at least lets you do namespacing and cgroups reasonably well and in a straightforward way...
Mounts, etc.: let's not get into fstab and its idiosyncrasies.
Logging: let's hope you set up logrotate properly or you're in for a surprise.
And on it goes.
Systemd is not perfect. But what it replaces was god-awful and far worse.