SQLDataSource Control DataSourceMode

This is from the book "The ASP.NET 2.0 Anthology"

In a discussion in Chapter 3 on the SQLDataSource Control this suggestion is made

For simple binding scenarios, however, it's a good practice to switch your DataSourceMode from DataSet to DataReader.

but never states why. Does anyone know? Is is faster?

From stackoverflow

• The DataReader is faster and uses less memory.