Ability to create a not hierarchy drill down, that you can choose which dimension you want to detail the selected item. Eg. You have sales by state, so you can choose if you want to detail some state by product type or by store, or even choose if you want to see all your data by product type and so detail some type by state or store.
Also, create some navigation map, to show what drilldowns was already been aplied.
Alessandro Marcelino Santos commented
This also allow you to change the chart category