I use it all the time at IAH, and despite some issues when it was first launched there, it works well now. A couple of tricks that will help — At security, the TSA agent has to hold the phone at an angle where the screen does not reflect the overhead lights. Usually this means holding the phone perpendicular to the floor. Holding it parallel to the floor and aiming the scanner down at it usually means the overhead lights cast reflections on the phone's screen, which prevent the scan from reading the bar code. Also, at the gate, angle the phone up a little toward you so that the scanner's beam hits the bar code at an angle. Laying the phone down flat under the scanner almost never works. Angling the phone up a little so it's facing you works much better.

I love the new system and wish it would get rolled out at more airports. It's nice to not have to keep up with a piece of paper, and if this system could get widespread adoption, it would prevent a lot of waste generated by printing boarding passes.