Was in MIA on 22 October, expecting the usual nightmare to be worse than usual. However, immigration seemed to have nobody to deal with but our flight at the time, so it was straight up to the desk.
As others have noted, the actual fingerprinting/photographing process doesn't take that long if you don't have to wait in a queue, although I think it's a little bit more than the 15 seconds that the INS claim. It's a bit smoother and faster now than in February and March when my partner (non-VWP passport) first started getting hers done. But the problem really comes when there is a backlog of people to be processed - if you're in a queue that's 40 people long and then every person is taking an extra 20-30 seconds ...