Sounds like a hit. Evernote, for example, saw an 1,800% increase in their new-user sign-up rate.
But I wonder what the category and pricing breakdown is for those 1,000,000 downloads? How many were free apps that people downloaded for fun to see how things work? How many downloads were popular iOS games that have been ported and are less than $5? How many were $20 and over apps that were new to the person downloading?