My favorite feature isn't mentioned. It's a very tiny tweak to how ambient display works, and it makes all the difference to me. I've actually turned "Lift to check phone" back on again because of it.
Previously, the ambient display could too-easily be tapped or swiped such that the ambient display would become the full screen-on display. If you had the Smart Unlock body-detection enabled, that could easily lead to unlocking the phone in your pocket. From there comes accidental app launches, battery drain, etc. Also, ambient display used to present interactive media controls if you had a media player running, so you might accidentally tap "play" on your music app when all you wanted to do was check the time.
Now, ambient display requires a double-tap to go to the full screen-on display. A single tap or a swipe isn't enough. This makes a huge difference and makes it far less likely that I'll accidentally turn on the screen and unlock my phone. It also no longer gives you interactive controls on the ambient display, but still presents them on the full lock screen. No more accidental taps on media controls just because I want to see what time it is.
These changes seem very tiny, but represent a major UX improvement to a feature that always had great potential.