For starters, placing the Apple Watch in Theater Mode will mute the sound and turn off the lift-to-wake function so the device will no longer light up should you suddenly raise your hands in the middle of Rogue One or feel the need to reach for you opera glasses. The watch will still receive notifications, but they'll only be delivered via haptic feedback. If you absolutely must disturb the sanctity of the theater environment, tapping the screen or pressing the crown will still bring up the visual alert. In other words: Theater Mode is simply Do Not Disturb mode with vibrating notifications.
Finally, the Verge notes SiriKit is also coming to the next version of watchOS, which should open the door for Siri support in more watch apps and services. With SiriKit baked in, the device will be able to connect with Apple's personal assistant without the need to have your iPhone handy. Apple has not given a release date for watchOS 3.2 yet, but the company might want to make sure it doesn't brick anybody's timepiece this time around.