To tag on to what
@mcraeh has said...the fingerprint sensor is as good as the iPhone - for me it is right there as an equal. Up to this point iPhone has had the best sensor.
I like the idea that it serves no other purpose than to unlock the phone or with a long press to lock the phone. I use onscreen navigation buttons (Pie Pro) and wish I could hide the stock nav keys but oh well.
The phone is basically the same height as my iPhone 6S Plus and Note 5 so size is okay for me. I have the Tumi battery mod on currently (brushed metal, feels good in hand) and as noted the sides of the phone get warm with use (heavy use, downloading, setting up, etc). However, the wireless charging with the battery mod is great and has worked with 3 of my wireless chargers (including the Samsung fast charger that I use with my Note 5). It also did appear that the battery mod did charge while placed on my wireless charger without being attached to the phone so that is a plus (I think LOL)...
Use so far - very smooth, no lag or hang-ups - really seems to handle app switching and tasks with ease. Again, only day 1 so further use might change that.
The thinness of the phone is awesome but without the battery mod on, it would be in a case cause that is how I like my phones but I can see several liking it naked. The camera hump, its there but doesn't bother me - with the style shell on or a case, it blends right in.
That's it for now - will put up more later. If anyone gets a chance for some hands-on with the device - definitely try it out and post up what ya think!