I have been using the mobile ticketing for my season ticket this season. From my experience it has been pretty good, bar the two week gap prior to the Norwich game. For some reason the ticket disappeared from my Google Wallet and when I tried to download again it wouldn't work. Had to go to the ticket office who gave me a paper ticket for the game, then emailed me another link a few days later to download the ticket to wallet again which has now worked. I have never had problems entering the ground, queues no longer/shorter than previous seasons.