It's the highest passenger traffic airport in the world, according to the internet. I don't know if I buy that (surely Hong Kong or something is busier?) but it is very large.
Delta hub, arrival & departure
Current Grade: B+ (Jan 2019)
Go early. You go through security (and – busiest airport – it's going to take a minute, they're efficient but overrun), and THEN you must take a shuttle train to your gate. I've been stressed more than once. But they do run you through pretty quick.
Amenties... nothing luxe but everything you'd need. There's a lot going on here.