I found Nanny a very interesting character also. But, the fact that he "wore metal bands around his wrists and his neck" made me think that he was a slave, not a robot. Also, something about the discussion of transgenics made me wonder if Nanny was a kind of transgenic, specifically designed for enslavement and servitude....
Otherwise, I found the story lack-lustre. The little girl was just not appealing to me - she was obviously calculated to be cute, but was really just a stupid brat who could have gotten herself killed. With that in mind, the ending was just too pat. I feel she needed to learn a lesson from her rebellious escapade, not be rewarded with an elevation to adulthood (in her own mind, at least).