Here is a nice video on how to use Power View in Excel 2013. I cover it in my upcoming Building Dashboards with Dynamics GP 2013 and Excel 2013 book too.
From Data to Insight & Impact: Building a Manufacturing Summary with Power View
SQL & DataSales, Purchasing & InventoryGP 2013
Archived post from 2013. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.