Physically, the Nexus 6P is a beast, size-wise, which introduces a steep learning curve in handling and operating it, for users not used to dealing with phablets. They have really worked on reducing the thickness though, making it super sleek, barring the camera protrusion. The fingerprint sensor placed on its back, is located fittingly enough to unlock when the device is in your hands, but is rendered useless when the phone is lying on its back, which happens more often than not. The unlocking itself is snappy enough to be effectively usable. Appearance wise, the metal body makes it easy on the eyes, but does not lend it the sturdiness you would expect. I personally was not satisfied with the build quality, especially considering it is metal, and would like for Huawei to make improvements in this area in their next venture.
The camera on the Nexus 6P is what makes it stand out from its competition in my opinion. It has a 12.3 megapixel camera, however the inherent pixel size for the 6P is larger than any other phone, allowing more light, hence giving much better pictures in low light. Digital image stabilization also works pretty well making taking sharp photos a breeze. The addition of slow motion video captures is a good feature as well. Of course, all the previous tricks such as lens blur and photosphere all work just as good, if not better. The camera performance in itself is also very smooth, and this is something that can be said for all operations on the Nexus 6P owing to the blazing specifications on the phone.
In terms of integration, I did not notice any significant improvements or changes in the 6P. I felt no difference in operation while using it with my LG G Watch R (reviewed, here), which is good considering this is a non LG phone, but bad in the sense that the random disconnects with the watch still persist, requiring occasional restarts.
To summarize, the Nexus 6P is a beast of a phone, with decent looks and no complaints whatsoever in performance. The primary improvements come in terms of battery performance and camera operation and snappy fingerprint sensing. For users having an appeal in these areas, the Nexus 6P makes for a worthy upgrade.