Here is the one more new feature I found from Android Dev Preview 3. Google has changed so many things in this update. They also made some design changes in this update.
Here is the new Animation, which I found from Android N Dev preview 3 update.
It's seems like Google preparing Android N for the final release. They refreshed Android's System UI icon.
One more thing I have noticed in this update, which you can also see in Android Dev Preview 3. IF your phone or tablet is running Androi N Dev Preview 3, you'll notice the old animation. Because new animation is currently hidden away in the recovery mode in devices running DP3. Running it makes it look like things are being erased and the system updated, but it's just dummy text. Once the animation is finished, the phone or tablet returns to the recovery mode. I believe we are attempting to get a video shot of this, so standby for that.
Some information is from AndroidPolice.com