Used it at SEA on Saturday. SEA was a zoo. As we exited the plane, everyone was held up which was probably because the immigration lines couldn't handle any more.
The guy holding everyone back yelled out several times that US and Canadian passengers with a smart phone should download the Mobile Passport App. Saying, with it you can bypass the long lines.
This was the first I had heard of this app. But I got it downloaded via a weak T-Mobile signal to my iPhone. Started filling it out just when we were freed to continue to immigration. I went to the normal line and got the App's form filled out and took my own photo to add just as I reached a point in line where I was able to jump that line over to the special Mobile Passport line.
But I still needed to upload the completed form and it wasn't succeeding. Finally switched over to the Airport Wifi and got the form uploaded just as I reached the security agent.
He had me scan the bar code that the App presented, and show him my passport. Handed me a card to present at the exit after claiming my luggage.
Got my bag and then found another long line to exit. When I got to the front, the security agent saw the card that I was handed and motioned me to go to the Global Entry lane which had no one in line. If only I had known this before. There was no signage that would indicate that Mobile Passport users should use the Global Entry line.
Now that I got through it all, it should save a lot of time next opportunity. You can save your Passport Profile in the App with a Pin number. Logging in has all the personal information previously entered. So you just start a new Trip and enter the Airline and Airport. There was something about the entered Trip information being valid for up to 4 hours; so I think next time I should be able to complete the form while taxiing to the gate. Then hopefully breeze through the lines.
Until everyone starts doing the same.