1) Speed does matter. Fast boots are good.
2) The new journal is just better. Finding something in the logs is easier.
3) Service files are easier to write than init scripts and one can have more confidence they will work as intended as you need write very little configuration oneself.
4) Knowledge of dependencies means I never have to worry about starting dbus before gdm. It just does what is necessary to do the correct thing.
I personally want all of those things. I am really happy they came to Arch and Fedora. They both feel much more modern for it. Working on systems that use older init systems now feels archaic.
Let's move with the times. I remember the same set of complaints when we got NetworkManager. I remember the same complaints with PulseAudio.
Guess what? I now have systems with excellent networking and excellent sound.
If NetworkManager is an example of how great systemd can be, then I just became vehemently opposed to it.
And this is perfectly the reason number two why i won't switch to systemd (reason number one is there is no need for it). PulseAudio does not work. It sucks. The irc channel is full of clueless (but trying to be helpfull) people. And nobody cares. I want my Alsa back. But now it's too late, i hope systemd will either be better (doubt it) or never be this popular.
And, I cannot lie, I don't want it because I don't want another dbus. freedesktop, stop turning my linux into a single user os. Next thing is they want to abolish x11. Sure it's about time for x12, but wayland? I just don't understand the community that surrounds Linux anymore.
But I don't have any issues. I don't have high CPU usage. It just plain works since various years.