I had a chance to play with the Pixel XL and I left with mixed opinions about it. The overall build is premium feeling and the construction is well built but the overall design has yet to grow on me. I will admit that it looks a lot better in person than it does in online rendered images but the design is still relatively "safe" and not exactly eye catching.
In terms of performance, the Pixel is easily the fastest android device I have used and it easily bests my S7E in UI Speed and app launching. The only concern I have is that the demo device I was able to play with for 10 minutes was warm to the touch and that was with what I would consider basic use. It could be that the phone itself is still indexing or completing set up in the background as they did mention they only received the demo device today and removed it from the box this morning.
I'm actually able to comment on battery life but since this would be the first charge on that specific Pixel XL I am not certain with what charge the battery came with. The battery history shows approximately ~90% as the start of the graph. When I handed the phone back it was at 56% battery with 2 hours and 14 minutes of screen on time. This is without an active SIM card and only WiFI connected but that is about what I could get with my S7E when it was brand new.
I did take a few pictures inside the store and the capture speed is quick but I noticed that if I take an image and quickly tap the image icon in the lower corner to view the image I just took. The gallery would still show "Processing HDR+" and a sort of foggy glass effect over the image almost as if the image is not yet loaded. This was relatively hit or miss as sometimes it took a few seconds for the image to finally appear while other times it didn't show the processing message. It's not a big deal but it's something I don't really like especially after being used to the rapid fire image capture on the S7E and the 7 Plus.
I also feel I should mention that white balance tended to a slightly yellowish hue while taking images in store. The lights are very bright and harsh so I can't draw any concrete conclusions but it seems like the 7 Plus I'm using presently did a better job selecting white balance. Overall, the camera app is a major improvement in usability over the Nexus 6P which was frankly embarrassingly slow.
With all of the above said, I'm not sure where my final standing is on the Pixel XL but I am extremely happy Google is putting pressure on the other Android device manufacturers to produce better devices. Hopefully this pushes Samsung to actually optimize and bug test there software before releasing it to the world. As frankly there is no reason Samsung can't produce a device as quick and fluid to use as the Pixel especially considering the manpower they have.