Sometimes, the interface will not allow me to play a card or activate an effect at the correct time due to actions taken by the real or computer opponent. For example, I tap on an artifact with a triggered effect to see the detail and hit the “activate effect” button. however, if my opponent takes an action at that moment, the game will “zoom out” from my card so the whole field can be seen again. I have lost several duels because of being repeatedly unable to activate an effect at the right moment. There is a way to stop the timer to allow you more time, but if your opponent is quick at changing phases, it can be difficult to use in time. Other than that and a couple buggy/errata type issues that will probably be addressed in future patches, I have no problems with this app. Beautiful to watch, fun to play.