For various reasons it seemed like a good idea to pop their app on the phone a while back, though as I described recently when trying to actually book travel. it caused some frustration. However having just had another look while idling away a time of waiting, I discovered our recently booked itinerary was available in all its glory. There is little to beat actually carrying printed copies of documents, but having the electronic versions available 'live' could be incredibly useful.
I'm also reminded of our trip to Italy some years back, where our hotel had closed and we needed to re-book mid-trip. This would have been so useful then, though I hope we don't need to do that again.