I noticed customs was a breeze yesterday in JFK T4. Used the mobile app since my wife and daughter don't have GE. There was only 1 lane open for it, but the wait was less than 10 minutes. All other non GE US citizens used kiosks which also looked to have a short line (there was a bunch of international arrivals at the time - maybe 8 flights on the baggage claim TVs.)
In the future, I think the app may be superior to GE, since any time I've used the GE kiosk, the facial recognition doesn't work so I have to go to an agent anyway.
Passport control didn't bother to scan the code the app generates in lieu of the form, and I had declared food, which I would think would trigger questions to make sure it wasn't meat or produce (it was not). All he asked us was where we were and for how long and let us go without any other questions. After baggage claim, there was just 1 agent patrolling the customs exit who also didn't ask for the app or any other exit info.
There was nowhere pointing me to declare something if I wanted to! It reminded me of European customs.