The Google Pixel has an amazing camera. I've spent quite a lot of time inspecting and analyzing some Pixel XL sample images on dpreview.com. The camera certainly has its cons and pros.
For example, I zoomed in 100% on some ISO 50 sample images, and I've noticed that there are some artifacts which are clearly visible when you view the image at full scale. It doesn't seem to come from oversharpening but from image chroma noise. For example, there is a closeup image of a flower and you can still see the noise in the sky and in smooth areas, like the flower leaves. You will not notice it when zooming out. So in general, I was expecting to see a cleaner image at 50 ISO, but I assume this is due to HDR processing. It's more evident in some images, while on other images it's less visible.
Don't get me wrong, the Pixel sample images at ISO 50 are very sharp and relatively clean, it's just that at 100% details, you can clearly see the imperfections, like the blurry details at the corners of the frame and some loss of fine details there. The center of the frame is very sharp. You can really read the fine little small letters on the street signs. It's not tack-sharp, but very sharp. If it wasn't for the chroma noise, I believe that even the tiniest letters would be tack sharp.
This tells me that the Google Pixel rear-facing camera have a high-quality optics, and that's apparent noise that we see, even at ISO 50 id due to the size of the pixels. Even at 1.55-micron pixels, the small sensor still cannot provide a very clean image, even at based ISO. This is true to most smartphone cameras, by the way, it's not that something has gone wrong with the Pixel main camera, it's just that to overcome this, you really need a bigger sensor with larger pixels.
The images coming out from the Pixel camera is just out of the ordinary, with bold saturated yet natural colors. I personally really dislike images with low-contrast and the Pixel camera just manage to make every photo, no matter which angle you took the image, look extremely good and full of life., sky looks beautifully blue, I didn't encounter any overexposed areas, even in one image that was shot against a strong front backlit image, the image still had high contrast and was very uniformed (image 42).
Even at high ISO, like in image 48, HDR really helps to promote excellent results. There is still a good amount of light in that scene and int those areas, it's hard to see image noise. However, in a darker area, like in shadow areas or when shooting outdoors against a black sky, you can clearly see a much higher degree of noise (like in image 6).
So overall the sample images really showed how good the Google Pixel camera is. Don't expect super clean results even at base ISO, but for a mobile phone camera, this is an amazing performance. I think that those sample images really demonstrates what Google wanted to achieve here. It used a 12MP sensor to keep a good balance between details, image quality, and low-light performance, and indeed this balance is visible when analyzing the sample images.
The lens does have visible distortions. You can watch objects outside the center of the frame (like in image 47) and you can clearly see that the distortion starts not so far from the center of the frame, not just the corners. This isn't unexpected from a wide angle lens and what you get with most phones by the way.
Overall I'm very pleased with the Google Pixel main camera sample images. Images looked colorful, balanced, well exposed and sharp.
You can view the sample images on dpreview.