I got mine delivered by FedEx today. While restoring it from a backed up version it got HOT. while holding it in my hand with my old 6 the new 7 was at least 15-20 degrees hotter. I called up apple care and I'm going to exchange it tomorrow. I've only used iPhones the last 8 years and I've never had this issue.
By the way, the new home button is terrible.