The emulator works full screen on a Windows platform where you can test out/use all your own apps that you have on your phone/tablet (paid and unpaid).
You start off with installing the emulator which creates an account with the BlueStacks cloud. Then it provides a PIN. You then download and install the BlueStacks Cloud app on your phone, put in the PIN and then you can export out all your apps and it automatically appear on your emulator.
The good features are for the developers so they can test thing out on a bigger screen with keyboard support. For me its providing a good platform to do app writeups on various applications with excellent screenshots. Here are a few of them:
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