>>966389 (OP)
There's a LOT of reasons why people don't like it, and I think the people who don't like it all likely have their own reasons for not liking it.
Here's a posting about someone discovering a massive memory leak that used up 4GB of ram. While I have yet to see something this massive, I have definitely noticed Systemd using more memory than the alternatives, and some leakage here and there as well.
https://serverfault.com/questions/755818/systemd-using-4gb-ram-after-18-days-of-uptime
Some see it as an unnecessary security risk due to its massive attack surface. It recently hit 1 million lines of code.
https://www.phoronix.com/scan.php?page=news_item&px=systemd-2017-Git-Activity
Some don't like it because they dislike its habit of scope creep. The project ends up assimilating things that historically should not have anything to do with init. gif related.
https://suckless.org/sucks/systemd
There's also some other design decisions that people have an issue with, such as using Google DNS by default (because of course systemd can handle DNS), using binary logs, etc.
Lastly there's the conspiracy theory side of it, which alleges that systemd is an NSA attempt to compromise GNU/Linux, and due to Systemd as a project moving way too fast, it can't be properly audited.
https://web.archive.org/web/20170724100245/https://muchweb.me/systemd-nsa-attempt/
For more links and arguments, see:
http://without-systemd.org/wiki/index.php/Arguments_against_systemd