The standard Income Statement lets the user choose a Fiscal Year and Period and compare its data with some other periods' data by selecting an option from the dropdown. The dropdown only offers a few options e.g. "This year/Last year", hence limiting the use of this report.
My custom version lets the user choose another Fiscal Year and Period for comparison, as shown below. Hence the user is not restricted by any select options in a dropdown, which provides a great deal of flexibility.