It is only possible to enter the game with wifi connection, if it is not in range or disconnect from the network, the game simply does not respond.
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In version 0.1 the workaround no longer works. The game will not run at all without active wifi.

In my situation, LG G3 (LG-F400S / OS 6.0 Marshmallow) happens with this issue. Cannot enter MCPE without any network connection. Only available when network is connected to phone. Still, for example, Wi-Fi connected, but if isn't connect to Internet, crashes. Checked in alpha v1.0.3.0. Need to be fixed ASAP.
It is related to XBox account connection, and Celluar Data also allows you to enter game. I already reported it so this is a duplicate. Lazy to find the issue now tho.
You can log out for now if you want game to run.