Today we pushed out an update to the Store app that adds some initial reports about orders. 

The main reports page shows a chart of the orders in the last 30 days. On the right are links to the other two reports. 

The Orders report shows a chart of orders over a specific time period. You can easily adjust the date range by using the fields above the chart.

The Products Ordered report will show products ordered over a specific time period with the products with the most orders at the top.  The number of products ordered show next to each product.

If a product has product options then you can simply click the triangle icon next to the product name to see the specific options that were ordered. The quantity for each product option combination shows next to each product option.