The big plus for the BerryStore over the BlackBerry App Center is that it is not supported by the carriers. It simply is an application that you install on your BlackBerry from which you can install and review third party BlackBerry applications.
The issue that I see for the BlackBerry Application Center is that carriers simply won’t support many of the BlackBerry applications out because a bad experience from said applications will reflect on the carrier. My guess is that the certification process for getting into the App Center will be much more stringent than getting listed on the BerryStore.
All you have to do to get into the BerryStore is create an specially formated xml file called a BerryStore Appcast that points to your OTA BlackBerry download.
The BerryStore is still in beta and only supports free BlackBerry applications as of right now, however, the ability to charge for BlackBerry applications is something that the BerryStore is working on.