As a non-US citizen who travels with carryon baggage only, this service is amazing. Instead of waiting a long time (often 30+ minutes) in the general foreigner passport control line and customs exit lines, I have been able to get straight thru without any waiting. I was extremely pleasantly positively surprised when I was able to use this the first time at ORD.

Another time I could have made my connecting flight easily from a slightly delayed international flight, if this line had been open. The long usual lines meant I missed the connecting flight and had to be rebooked for the next day.

Maybe most of you are US citizens and/or have access to Global Entry, so this doesn't help much?

I'm wondering a bit how useful this service is overall, as it can not be used by most arriving international travelers with checked bags. But it is definitely great service for carryon-only travelers to/thru the US.