[Google Pixel 2 Guides, News, & Discussion] jallenhayslett:
I started this off as a response to another thread inquiring about bugs or issues with 9.0, but ended up writing up a full piece about the useability and functionality of the system and decided to make it a new thread. In short, I suggest to anyone considering the update, if you're happy with your current set up and are not fond of relearning how to use something you carry and depend on every day, then you will probably want to stay on 8.1.

I used it from the day it released up until 2 days ago and found it to be a massive clusterf*ck of UI/UX inconsistencies, glaring white, and broken useability features. Notifications are a mess, settings and features which were organized into reasonable categories are now buried in unrelated submenus and renamed confusingly, reliable UI/UX features have been swapped with newer less obvious actions, gestures, and unclear UI elements, drastically unrelated font families have been thrown together to create a very visually jarring reading experience, the system UI has enough white-on-white you could use the phone as a beacon in a storm, and the color choices seem to have been based on focus groups conducted with toddlers. Maybe it's just me getting old and stubborn towards change, but the consistency and predictability of 8.1 is nowhere to be found in 9.0.

As for the backend, a lot has been added, more than I can recall or understand, but the PrivateDNS and MAC randomization are nice security upgrades that are actually useful for those who live in places with ubiquitous but often sketchy, less-than-open internet fuctionality. It is noticeably faster visually, but also particularly faster in dealing with larger files and database types of information. Small tweaks, like the media volume default, and the dynamic rotation icon in the navbar, are welcome additions, but those come at the expense of the god-awful, take it or leave it, reworking of the Recents overview page. I know it's currently optional, but I gave the new gesture system a go, and eventually got used to it. However, it's going to take some massive tweaking down the road for it to be anywhere near as efficient and simple as the old navbar and vertical card overview.

Core device functionality is fine and battery was fair, almost the same, but I run a very lean system and also disable a lot of services since I currently live in a country with restricted Google access and most of those features are useless to me. Camera is still best-in-class and shouldn't be expected to change since the core camera functionality is in the hardware, the Camera app, and the Pixel Visual Core extension app. Basically any system apps that update via the Play Store should and do function as expected without any noticeable problems. While not specifically a Google problem, it's still worth mentioning that some apps are not yet ready for 9.0 and need to be updated by their developers.

My personal opinion, 9.0 is Android's "Windows Vista" moment, and they'd be smart to pull the whole thing back to beta and hold the release until they get their UI/UX overhaul ready for a full primetime roll-out. The system runs like it was built and tuned specifically for the Pixel hardware, but the user experience made me cringe every time I picked up my phone.

I spent the last 36 hours downgrading to 8.1 from a full wipe, clean setup, and restoring an adb backup. I now have a phone that I actually enjoy using again and I couldn't be happier with it.

Edit:

In considering a few friends opinions regarding Betas and Developer Previews, I'm inclined to temper my opinions, but only slightly.

Yes, I agree, that taking part in the Beta and Developer Preview (DP) process of OS releases helps determine many important aspects of the OS. However, in the case of entities this large, that involvement is really only meant to be as bug chasers. Beta and DP user's opinions on UI/UX matters are largely ignored, as they do not fit within the framework of said entities larger goal: Mass Usage (i.e. the lowest common denominator, AKA the ignorant child-like masses). They only want you for your ability to create and willingness to report showstopping bugs. They don't need the developer or niche user community to make UI/UX choices, they have focus groups for that. Unfortunately, the customer isn't always right, and people don't usually know what they actually like or why. Chase opinions, focus groups, ad engagement, click data, and the fastest dollar, and eventually we'll all be living in a Fisher-Price world (see: Asia).

The second problem with participating in these not-really-beta and almost-but-not-quite-developer-previews is that, not only have they already made all of the major decisions about how it's going to look and be used, expert use and experience be-damned, but by participating in these programs, the user is effectively subjecting themselves to a brainwashing scheme meant to dull the discerning mind into believing that "vX.X is so much better now than when it first hit public preview". It's the equivalent of software Stockholm Syndrome. Public Beta and DP users have deluded themselves that this final release is ok based on how they saw it change from the first public preview release. It's still just as awful as it was when it first went public, it's just a slightly better shade of awful.

It's a damned shame such a powerful and well running OS feels like it had such an awful UI/UX thrown on top of it. It's inconsistent, half baked, and feels like a grab at the ignorant, screen-obsessed masses, if they were color-blind with 20/200 vision. This is professional grade coding with pre-alpha grade UI/UX. A system built for power with a GUI designed for infantiles, on a device aimed at enthusiasts. They should be ashamed.