I'd only be afraid of checking the wrong box and sharing with one or more of the wrong circles. This could easily become much more then a fun social experience. I am very excited to see where it goes. With Facebook I'd be hesitant to add co-workers as friends or to make certain posts. Now I feel I may be able to keep family, friends, and work life separate in one spot. Facebooks goal of being a one stop website may have a strong competitor here and o truly hope it does.