As a Brit I entered the US at TPA using GE for the first time a few weeks ago. The kiosks are easy to find (sharp right when entering immigration hall) and use. Just follow the instructions on the screen and answer the questions. There's no need to complete the hand-written customs form as the machine does it for you. I was through immigration within minutes and got to the customs area before my wife, who is a US citizen (but does not have GE), even though there were only a few folk in the citizens line. It was quicker than coming into the UK on our return. I was very impressed.