I don't think much of the interface, including the flaw that if the opponent chooses not to block, it doesn't let you respond (e.g. by pumping up an attacker, etc.). However, once you get used to it, the game play does scratch the MTG itch.
However, since updating to the new expansions, all I have been able to do is play the story mode (which I do like) and story quests. Every time I have tried to battle, I either get a system crash (Duels closes and bumps me to the main iPad screen) or I get to the "deck loading" screen (for the AI opponent) and it gets stuck there.