I recently experienced the preclearance in AUH for my flight to JFK. Note that its only flight 101 to JFK that gets the preclearance because flight 103 is operated by Jet Airways and doesn't qualify for preclearance. Overall I was extremely happy with the arrangements. Left the lounge at 9am and walked till the end of the corridor where the US preclearance area commences. Priority lane is present for premium passengers and a staff checks all the documents to find out if someone has the SSSS mark and if so , someone takes you to a separate security area. Once you clear security then you proceed to immigrations whereby a new technology gives the officer a view of your bags and thereby clears customs at the same time. We didn't have to wait long and then you go towards your boarding gate where again premium passengers have a separate sitting area. For me it was a real relief to land in USA as a domestic passenger in the Delta airlines terminal and just take your bags and walk over to your complimentary limo. I will be using EY for all my future travels to USA mainly for the preclearance facility.