A small yet surprisingly good and useful Motion Sense feature is swiping your hand above the Pixel 4 to snooze an alarm — no looking at the screen to make sure you tap the right button. Plus, Motion Sense can tell when your hand approaches the phone and reduces your alarm's volume, too. This may seem inconsequential while you're reading this wide-awake, but it feels like a pretty great feature in the mornings, let me tell you.
Apart from that, the only other Motion Sense feature so far allows you to switch to the next track, which can be cool but gimmicky, and doesn't always work well. Otherwise, that's about all you can do with the gesture controls on the Pixel 4 so far. It's pretty limited, and you can already do a lot with your voice and Google Assistant, including switching to the next track.
It would be great to swipe your hand up or down to change the volume, for example. Or maybe use different finger gestures to navigate around the entire Android operating system and apps.
It's something that Google will surely improve over time, and I'd bet money that more comprehensive controls will someday come to the Pixel 4 or future Pixel phones. It's a pretty safe bet, as Google has already said that Motion Sense at the Pixel 4's launch is just the start.
Overall, Motion Sense is good because it's starting off slowly with just a few little features and functions. It's not overpromising anything, and it seems to have the best chance out of any other company's attempts to make motion gestures a "thing."