Jonny Evans at Computerworld has some neat tips and tricks for the Apple Watch. I knew most of these already, but this one was completely new to me:
A call comes in and you check your Watch. You know you want to talk to this person but want to use your iPhone to make it. Suddenly anxious you grapple through all your pockets to find your phone and the call drops. It needn’t be this way – just use the Answer on iPhone button at the bottom of the incoming call screen (turn the Digital Crown a little and you’ll see it). The person calling will hear a repeated sound while you search for your phone. Stay cool.
This is amazingly useful and I've already used it a couple times for incoming calls.
Dave Mark at The Loop adds:
This is designed perfectly. The moment you tap the “Answer on iPhone” button, the call is answered and Siri’s voice says, “Please hold on a moment”. Then, a series of repeating tones plays, that makes it sound like you are on hold. My instinctive response was to stay on the phone. This is great.
I have no doubt I will get a lot of mileage out of this unsung hero of a feature.