WorldVision has brought food, education, medical care and provided for basic needs for hundreds of thousands of impoverished kids around the world. By doing so in a sponsorship way, they have also helped to raise the awareness of Americans and others about the economic conditions in many countries.
They have been criticized by some charity watchdogs as having too high of salaries for their executives, and high overhead costs that limit how much of every dollar donated actually goes to the people sponsored, but they have still done a world of good (no pun intended).
World Vision has great success as they address issues from mal-nutrition to AIDS to clean water to education. Having an organization in over 100 countries that serves over 100 million people is a pretty dramatic undertaking. To affect that many people is commendable, not to mention that their organization creates jobs in several underdeveloped countries.
Being a faith-based organization, their purpose is as a result of a tenant of their faith which is to serve others and meet their needs. The organization does not promote their faith and additionally respects the faiths of those they serve.
World Vision has experienced minor criticism for not meeting the specific criteria they offer for the sponsorship children that they serve. People want to know that their dollars (usually about $30/month) are going directly to a specific child. When one sponsor actually visited their child, they found some of the information about the child to be not true. Furthermore, the child had no idea that they had a "sponsor".