I have never enjoyed the idea of extensions for essential functionalities like power menu. With release of newer versions of Gnome Shell every 6-8 months, extensions break. Like Firefox, there will always be some extensions not working. You have to log-out to enable extensions. I don't like to reboot or log-out my Linux box, not for trivial things like extensions. I only reboot when there is a kernel update.
I am still unable to understand where do they want to take notification.
I like both Gnome and Unity. Gnome Foundations and Canonical should be left to pursue their own objective goals as long as they don't destroy projects that are used by other Desktop Environments like XFCE, etc.