Does exactly like it says Puntuado con 5 de 5 estrellas

Good, but on Android 4 and higher you can close Firefox with the app switcher.

Esta valoración es de una versión anterior del complemento (1.04.1-signed.1-signed). 

This is true ! And was discussed internally quite a bit before deciding on the change. (They knew there'd be people like me :P ) I like the exit-from-app method as it feels cleaner to me than switching to the OS.