I must say I am impressed with Global Entry application process.
I decided to apply when I got stuck in Immigration for 90 minutes in ATL and almost missed my connection. I saw a few people using the kiosk and was totally envious.
I am a citizen of Germany and Chile, with a green card. I applied on August 9, got approved on August 12, scheduled my interview in ATL (Terminal E) for August 17.
The only (minor) negative I noticed is that they don't take it too seriously with the appointments, since, theoretically, they only schedule one person every 20 minutes, but right after I arrived, three people arrived at the same time. Had I arrived about 10 minutes later, I might have missed either the appointment or my flight. So plan accordingly.
When I got there they asked for my two passports, green card and driver's license, which was the proof of residency.
I had to wait about 20 minutes for my interview. During this time they entered all my information to their system. During the interview, which lasted no more than ten minutes, they asked a few questions, took a picture and my finger prints. Then they put a sticker on the back of the green card and showed me how the kiosk works in a test kiosk.
I have not used it yet in real life yet, but I believe this is going to be worth it. Next week I will be able to use it for the first time, when I will be returning from a trip to Europe.