Really cool in terms of rebasing and rollback, but Flatpak isn't there yet (for me at least). Introduces lots of complexity without much benefit for me. They have their uses, but not for me yet. And honestly, I haven't bricked my system in long enough that I don't consider it a benefit I really care for.

Don't get me wrong, they are cool, and I hope development is continued but they aren't for me just yet.