The Facebook new app store, is available at www.facebook.com/appcenter and is not a store in the true sense of the word. It’s more like a list of best apps available on Android and iOS, which Facebook indexes and show them to you.
Until now, we found only 600 apps and web apps, in the App Center, but we expect that number to increase substantially in time. I don’t think App Center from Facebook will match Google Play or the App Store when it comes to available content. See more for news video.