One of the wasted opportunities with Apple Watch is the limited Siri functionality compared to iOS, which means apart from basic queries the watch always told you to perform the action on the iPhone.
That's about to change with the upcoming watchOS 3.2 update, which would finally bring SiriKit to watchOS. SiriKit is what enabled iOS to integrate with third-party apps so you could, for example, call for an Uber or send a message on WhatsApp using Siri. With SiriKit on watchOS, you will be able to perform all these same actions on an Apple Watch without having to pull your phone out.
Along with SiriKit, watchOS 3.2 is also expected to bring Theater mode, which will disable waking up the watch every time you move your wrist to avoid annoyance in dark places such as cinema halls.