Everyone is always snarkily saying, "customs is nothing, just a walk through, you mean immigration" when talking about queues and hassle-- well, they ain't landed at Dallas DFW if they're saying that.
Yesterday we landed at DFW from Cancun. I used the mobile pass app to speed things along and for the immigration section it did. They WAVE YOU PAST the whole immigration section without EVEN A GLANCE at passports for the five of us. At his point I'm thinking, "That was a breeze." Wrong.
Then down a level (or maybe two, the place is a labyrinth) to baggage claim and a massive people jam. The baggage from all the flights (Doha, Beijing, Belize, Cancun) were sent to the same carousel, then huge queues for customs, one for US citizens, one for others, and then a special gate for global entry which seemed to not have any check. Then the customs person did the full passport check for each person coming in.
A strange and hopefully not to be repeated experience.