I really like it as well. I did three major version upgrades so far and they have been flawless. I also really like Flatpak, finally a way of easily installing something on Linux without breaking half of the system because the application you wanted to install uses libfoo 2.0 and not libfoo 1.9.9-patch-1337. With my atomic desktop applications that worked yesterday also work today. Things don’t randomly break all the time.
The future of Fedora Atomic also looks exciting; Timothée Ravier is working on sysexts which are a way of installing applications without ostree layering. I could remove most of my ostree layered packages with that.
Session is a Signal fork and they removed forward secrecy which makes them vulnerable to Key Compromise Impersonation attacks.