There are A LOT of improvements (e.g. session management, dynamically spawned services, networking, bluetooth, thunderbolt) which were made possible by systemd,

There are A LOT of improvements (e.g. session management, dynamically spawned services, networking, bluetooth, thunderbolt) which were made possible by systemd, udev and dbus. I'm not saying that UI/UX is good. It sucks. It does not improve that much over time. Also Canonical made things worse by rolling out snapd which is unreliable and hard to setup non-ubuntu distros (e.g. it tends to drop its state on Gentoo)