Some of the advancements Android P brings to Google's mobile OS include improved indoor positioning for location-based apps, advanced tools for phones with dual cameras which includes seamless zoom, bokeh, and stereo vision, display cutout support, more intelligent autofill, inbuilt support for HDR-enabled movies and an overhauled notifications system.
Read also:Android Oreo 8.0 Features
That last one is where most of the everyday, customer-facing improvements lie: there's a revamped visual interface and a new MessagingStyle tool that highlights who is messaging and how you can reply. If you like communicating on your phone with others, this is a big deal.
For a more thorough overview of what's new in Android P, head to the official Android Developers blog. (It's chiefly aimed at app creators but still gives a pretty good idea of what customers can expect from the OS.)
The Android P Developer Preview is currently only open to owners of the Pixel, Pixel XL, Pixel 2 and Pixel 2 XL. You can grab download links for each phone from Google's website. (If you don't own one of the aforementioned phones, you can still check it out via an Android emulator.) You can find step-by-step instructions here.
Please note that this is an early baseline build for developers only - You are best encouraged to sit tight for the final release version. Also bear in mind that installing a system image on a device removes all data from the device, so be sure to backup your data first!