1.) I've had major battery drain issues since 16.11
I charge my watch daily because I use nearly all the features including music. Nothing wrong that personally just charged it while I eat dinner and showered and would go to bed with roughly 95-97% charge, wake up around 91-93%. Monday I woke up at 40% didn't even realize it was 40% until I had to look at my watch because my music kept shutting off. Which will be the 2nd issue.
2.) Randomly shutting off my walk/run/music.
I walk to the gym early in the morning (1-2 miles depending on the route I take) then work out, run, work out x2 and walk back home. So I use my watch constantly, but while on my walk to the gym on Monday I had to restart my walk 6 times by the time i got to the gym. I only knew because my music stopped as well and then my watch vibrated along with my phone to tell me that they had logged the activity. Did that once as well during my cardio routine and when was on my run. Again I only knew that it happened because suddenly my music stopped and I got the sync notifications.
3.) Brightness levels
I wear my watch at night and have a custom face on it along with auto-brightness enabled. The past 2 weeks I want to say it has been extremely bright to the point it has woken up my wife and I could use it like a flash light it felt like.