The app allows a break-out of sales by day, week, month (5w) and 6 months (26w). There are colorful graphs for displaying unit sales and updates. Additionally, developers can see information about the different markets where their app is sold.
Apple's iTunes Connect Mobile is a free download from the App Store. Note that it does not seem to have propagated throughout the entire store. If you don't see it yet, try again in a little while.