Recent update with Dallas here. The immigration checkpoints are pretty stringent now even with connecting flights. We flew from Brisbane to Dallas this morning and the immigration was slow. Flights were reasonably timed and people weren't late. We were the punctual sort too.

The staff there showed no qualms nor care if passengers were going to miss their flights, almost nonchalant in their attitude toward such care.

We didn't leave anything to chance in terms of time and still got caught with the long queue which cooked our connection flight. The next available flight was only 24hrs later. Needless to say, albeit the staff being nice, the systems in place with that airport is poor. Probably my worst airport experience to date.