I used GE for the first time last week at ORD. Arrived with other flights on the afternoon bank of EU flights. My friend did not have GE so she waited and I was in and out in about 3 mins.

Kiosk asked me to find my flight number and then select the city it came from. Flight number was found but not city, weird. No X on receipt and walked away. Balancing factor was wait for checked luggage but was waiting for my friend too. She waited about 25 mins at immigration line and our luggage came out just when she was coming over.

So without checked luggage very convenient, with checked luggage, could be hit or miss but still worthwhile to have it IMO