Smaller screen size and no dual front facing speakers are my two big issues. I really miss my almost 6" screen of the One Max. A few tenths of an inch smaller Nexus 6P doesn't sound like a lot, until you take those stupid on screen buttons into account. Now the Pixel XL is a few tenths of an inch smaller than the Nexus 6P. If the Pixel XL had it's current 5.5" display w/ capacitive touch buttons, I would consider that aspect of it a wash. I'll see what next years crop of Pixel's bring. The camera on the Nexus 6P is good enough for me, considering I don't use my phone to take pictures that often. My only problem is the annoying stutter with the camera, when switching from landscape to portrait. Battery life has been great and exceeded my expectations. Never really had any slowdowns, but I did do a complete factory reset after going from 6 to 6.0.1 and from 6.0.1 to 7, and I will do one when going from 7 to 7.1.
The price of the Pixel XL is also insane, Yes, it is inline with other flagships, but it's not inline with Nexus. If my Nexus 6P died right now and I was to spend upwards of $800 on a phone, I wouldn't think about it twice, I would go with the HP Elite Windows Phone.