One question that still looms over the Apple Watch is battery life. Apple has explained several times that you'll need to charge it every night. However, the question that hasn't been asked (or answered) is if I charge it overnight and strap it on at 7AM, will it still work at 9PM, or even 11pm? Is there some point during the day that my Apple Watch, starting with a full tank, runs out of gas?
This is a big deal. While poor battery life seems the way of things with most smart watches, the early adopters of those devices are a small group of nerds and understand the underlying physics. That isn't the case with the Apple Watch. There will be a lot of people buying the watch that never think about batteries and processors, and shiny screens. They just want their $500 Apple Watch to work and if it craps out at dinner time, there will be an uproar.
I don't think Apple can afford to get this wrong and I think they know it. I bet that this requirement for an all-day battery has been at the front of their mind throughout this product's development. There has been a lot of criticism that the Apple Watch is too thick. However, longer battery life requires a bigger battery and Apple is entirely willing to take the heat on the watch being too thick to keep the all-day battery. It's not just the watch's thickness though. I think nearly every component of that watch, from the processor clock speed to multi-tasking to the number of your heartbeats it records, are all set to preserve battery life. Apple nailed the Apple Watch in so many ways. Now they just need to make sure it will stay alive on our wrists all day.