I received my 6P a couple hours ago. Aluminum 64GB.
Some initial impressions (coming from an HTC One M8 running CM 12.1):
--I wish the whites were a tad whiter, I can never adjust to the yellowish whites on AMOLED. Besides that, the colors are amazing. sRGB mode is kinda useless. Everything looks muddy and gross.
--The vibration motor also seems somewhat faint, I recall there being a way to adjust that system wide but I'll have to look.
--The notification LED (once turned on) pulses ridiculously slowly and by ridiculous I mean you can't glance at the phone to see if there is a notification, you have to stare at it for a while. Light flow here I come.
--This phone feels glorious in the hand, it's the type of phone you look for any excuse to pick up.
--The front facing camera is exceptional, I look at least three times more handsome than I do in person in these selfies.
Some questions that have come up: do services like pushbullet prevent the phone from dozing? If you set the phone to screen wake at a notification, does that also inhibit doze? Mostly I don't know enough about doze lol.