Steven Frank’s cogent description of the App Store in its current state:
Specifically, you have a large group of people who will download and suffer any old shit by the bucketload as long as it is free or extremely cheap. And you have 10% of people who are actually particular about software quality and are willing to pay for it.
In other words, you have the Windows market, and the Mac market, but within the app store itself. And you’d better be damn sure which one you’re targeting, and set pricing and development schedule accordingly.