For comparing two portions they’re okay. For larger data sets it can be difficult to compare the sectors: http://upload.wikimedia.org/wikipedia/commons/thumb/b/

For comparing two portions they’re okay. For larger data sets it can be difficult to compare the sectors: http://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Piecharts.svg/689px-Piecharts.svg.png http://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Pie...