UNICEF has just published The State of the World's Children 2012. This is their annual flagship report, and the theme for this year's edition focuses on the experience of childhood in an urban environment. Information found in the report includes detailed statistics about children in different countries, features on children's rights, data on education and nutrition, and much more.
The full report is available from this link. You may also find this accompanying site useful, which contains plenty of supporting documentation. And full versions of previous editions of the report are available here.