Iphone 6s here, pubic beta 3. Watch with 2.x OS. Watch battery is so far beyond bad now its kinda funny. I charge every night. It will be dead by 5:15p most days. I put it on around 7am. And that is not using the watch for anything but looking at the time and seeing what just made my phone beep. I am not doing any working tracking on it, not using apps, etc.