As stated in the preview post, the 6P is undoubtedly the more premium of the two new Nexuses. It's got the larger, more dense display, the aluminum body, the higher-specced processor, the stereo speakers, and the higher price tag to prove it. And my experience with the Nexus 6P has proven that - to me - the phone is worth that price, even as an upgrade from the original Nexus 6.
The 6P demonstrates lessons learned from previous Nexus phones - it's big, but more restrained than the Nexus 6. It restores the pulsing notification light to the Nexus line. It has a camera that's objectively impressive, not just a camera that's good "for a Nexus."
The Nexus 6P is a really really good phone. If you want build quality, a great camera, a great-looking display, and the promise of fast updates, this is your option. If you want amazing battery life, expandable storage, or removable batteries, it is not. As with any phone, it comes down to your personal priorities.