[Quick disclaimer, I'm very particular about this sort of stuff.]
Owned the Icon for about 4 hours now, here's what I noticed. When messing around with the Nokia Pro Cam, the phone got really hot. Almost to the point of burning your skin hot. I was also downloading a bunch of the Podcasts at the same time, not sure if it's related.
Second thing I noticed, the keys are not consistently lit up, this was the same thing on the Lumia 928. Not biggie, but just bad quality control in my opinion.
Lastly, when pressing down on the back of the device, it feels like inside back is sticking up against the battery pack and then quickly unsticking making a squishy noise. It seems there's a bit of room between the inside back of the case and the battery. Once I receive a case for the phone, this will become less noticeable I hope.