And I would say Chromebooks value add is the same as any cloud-based service. It simplifies things by having everything done for you. No application installs and everything is constantly up to date. Also improves battery and device life since it doesn't need the same kind of power to run heavy apps.
Would love the option to make a circle public to its members. Say you want to organize a camping trip, you could create a circle and invite those people to interact within the circle. Doesn't seem to be part of the functionality right now.