With systemd, you have integrated resource limitation, meaning you can explicitly set nice level, OOM score adjust, IO scheduling class, CPU scheduling policy, etc., in the unit file for a service. You can see the different knobs available in systemd.exec(5) http://www.freedesktop.org/software/systemd/man/systemd.exec.html
I have a very old Pentium 4 machine acting as a web server (500 mb of memory!); sometimes the MySQL instance would consume all of the CPU, and the Apache requests would get queued until it brought the machine to its knees. If I was really patient I could try to get an SSH connection to zap the MySQL and/or Apache processes, but what I usually did was to ask the people nearby to push the red button and restart the machine. With systemd now I adjusted the CPU scheduling of MySQL, and I have never had the issue again.
Yes, I could do that independently of any other init system; but it's clearly integrated with systemd, and is really easy to set (and with drop-ins, you don't even need to worry about the upstream unit file changing). Only for that, I will not change again to any other system that doesn't provide, out-of-the-box, the same functionality. Or any of the other nice thins that systemd provides.