Passbook sounds great, but in practice it utterly and completely failed me today. I had 2 flights on United today so I downloaded their app and entered by flight information. As far as I can tell the United App was always up to date and correct. I added the passbook cards yesterday evening. My early morning flight was canceled and United automatically added me for the next flight out. Despite having the option to receive updates checked, I received no notice. I had to manually delete the card and re add the flight for it to show the updated information. My connecting flight changed gates and was then delayed. At no time did passbook ever update with this information. I had to once again manually delete and re add. Another thing that annoyed me was that all that ever displayed on the lock screen was a text sentence that said " United Flight XXXX Time XXXam/pm. So before I'll use it gain they need to fix the update issue so that it actually updates like it is supposed to. I also hope for flights they have the card display on the lock screen for an hour prior to flight departure.