Fifth and final developer's preview available on https://developers.google.com/android/images downloads page now.
The developer preview only runs on a handful of devices and is intended as a test platform for developers. However, plenty of curious enthusiasts run the developer previews as well. Those with a compatible phone can check out the (probably) final form of Android P right now.
Installing the developer preview means you’ll either have to sideload a system image over USB or wait for the Android beta program to get the update via OTA. The latter is easier, and you won’t have to reset your phone. The system image approach means you can usually get the updates faster. It’ll probably be another day or so before OTAs arrive for those in the beta program.
The fifth developer preview (also called Beta 4) is a release candidate. That means it should be feature and API complete, making it almost identical to the final build. Android P will bring features like smart replies in your notifications, a cool rotation lock button, an updated UI, AI-powered battery optimization, and gesture navigation. The gesture nav feature is optional and a bit buried in the settings, and for good reason. It’s a bit of a mess right now, even as we near Android P’s launch. The standard nav bar will probably be the default.
The updates in this particular update seem mostly behind-the-scenes. The APIs are final, so developers will be able to validate their apps on the new OS. Some consumer-facing features could technically still sneak in before launch. For example, Google’s digital wellbeing features unveiled at I/O this year are still missing in DP5.