Yesterday was the first "trial" for me out in the open without any chance to charge my iPhone or my watch if either failed me. Early to rise late to get back, the family spent the day at an amusement park on top of a mountain. Reception was poor enough in spots that I think that explains some of the hit that the phone's battery took, but the watch was strong. I got alerted of a few emails that I simply achieved as I haven't gotten around to filtering them or unsubscribing yet. (Rockstar is no longer bothering me as Gmail automatically deletes their messages. Hey, I tried to unsubscribe four times. I was generous.) I exchanged a few brief messages with friends while I was in line and I contacted my wife when we separated at a few points to speed up the whole amusement park process. I ended the day with a fair chunk of battery left. It does better when you're not fiddling with it all day as a new thing.
What the watch did not do was protect me from getting sunburnt. Piece of shit.