Compared to the airports in New York, this one is pretty clean. Staff are friendly, even when selected for SSSS, which is a secondary security screening where you pass through a metal detector and have your bags inspected by hand. There is free wifi, although sometimes it does take a couple of tries to get connected, and free iPads docked at stations (with additional outlets). There are shuttles between terminals and luggage carts to use. Overall, it's a very modern airport with minimal stress for an international traveler.
However if you are transitioning from an international flight to a US connecting flight, expect long lines and a 3-step gate system where you scan your boarding pass, scan your passport, take a digital photo, and wait again before going through customs and security. The connecting flights are in a dimly lit corridor with seats that'll make it difficult to not bump knees with your neighbors. There are also very limited food choices in this area. It's a bit depressing.