As far as I know it essentially boils down to systemd doing too many things.
Critics argue that systemd is too complex and monolithic, making it harder to troubleshoot. They worry about a single point of failure, as all services are managed by one daemon, and voice concerns about tight integration with the Linux kernel, which could limit portability to other systems.
I went to DL it and try it out, and… dude, I hate Sourceforge. I know how privileged this sounds, but I'm not spending a half hour DLing something that I can DL in a minute and a half somewhere else.