My experience:
- app was a little slow on location services. It knew where I was, it just took a number of seconds before it caught up to me.
- I had no service on the mezzanine level, so it wouldn't load the schedule (which I guess meant it couldn't send me notifications of a boarding gate)

The biggest issue I can see, though, is people staring at their phone and watching the map while walking around trying to find (for example) a place to eat. Seems like people will just be running into each other.