A possible hidden feature of the Apple Watch:
Depending on how well Apple manages the Bluetooth link with the iPhone, the Apple Watch could then effectively function as a wearable spare battery pack for iPhone users — if it ends up re-routing enough usage away from the primary mobile device to an auxiliary wearable.
If that’s the case, Apple’s 2015 party trick could be more slender iPhones with battery life that appears improved — thanks to a portion of mobile usage being re-routed to the Apple Watch — while simultaneously making more money from its user-base.
I’ve only had my Apple Watch for a few days, so I’m not sure this is the case. A full review is forthcoming though.