It works great through the app. Just be sure to check in with the customer service agent at the gate when you get there so they can clear you if seats are available. I didn't do this yesterday and noticed they started clearing folks out of order on the standby list (presumably because they were present at the gate and/or asked the CSA). It doesn't seem like they automatically clear you on to the flight like some airlines do. I made the flight and got C56 so it all worked out in the end.