Donut charts and pie charts are very similar and some would even say they are the same type of chart. I am in the camp that says that they are the same and therefore I have approached donut charts the same way I have approached pie charts. I do not use it.
The things about donut charts and pie charts is that pie charts are in actuality better than donut charts. Donut charts are basically pie charts with a hole in the middle. While this might not seem that big of a deal, it however reduces the amount of information that you are seeing and makes it even more confusing. For example in the figure above, by removing the center of each circle, the chart is presenting the information with only a tiny portion of information. It becomes harder to see the size of each section and how they compare with each other. Of course while the information about each sections size is represented as a number, this could have easily been done in a bar chart instead. So for future references, stay away from all charts that have a name related to baked goods. Its far more satisfying to eat them then to use them as a visualization tool.
Reference:
http://www.vizwiz.com/2012/06/donut-charts-are-worse-than-pie-charts.html