In recent days, it has surpassed 800 million downloads, distributed among the more than 25,000 programs currently available. That's a lot of downloads, and given that there have been around 14 million iPhones sold to date, we can surmise that people are downloading more than just one or two programs. On top of this, Apple's latest announcements indicate that they are trying to further build developer interest, making programs easier to develop and giving them additional ways to earn money.
Earlier this month, it was discovered that Apple is actively working to shut down third-party App stores, which they claim violate the DMCA. Given the incredible success of the App Store, you can understand why they'd want to protect a monopoly on iPhone programs. But is it really worth their time to chase down small operations that are trying to provide a service to people who are still Apple customers?
It seems to me that Apple really has two operating extremes. On the one hand, they offer a lot of great functionality and drum up a lot of excitement from their customers. On the other hand, they seem to be growing increasingly resistant to anyone who wants to work outside of the sanctioned Apple methods. For better or worse, they are doing things the Apple way.