I do not have an informed opinion on the different aspects of snaps, because I haven't had to deal with them at all.
That said, the feature "automatic updates whenever the system feels like it", is an annoyance for me, even if I can defer them. Typing "sudo apt full-upgrade" takes a few seconds.
I just use Ubuntu Server and get only what I need, which is available through the APT repositories. I have not noticed these repositories getting any smaller in favor of snaps and I am already using the 20.10 development branch. The Ubuntu Server installer does not install any snaps by default. However, snapd is there but it is trivial to remove it if one wants to. Chromium is the only "loss" I have witnessed and I also saw this mentioned in other comments. Note that there exists a really nice PPA, maintained by Pop!_OS, that contains quite a few packages, including Chromium.
I am wondering what security issues do snaps address that apparmor, whose purpose is security, does not. I also think it is unfortunate that we need snaps to deal with different applications / packages needing different library versions...