Here's one.
I don't like how the activity circles automatically reset when the watch is placed on the charger.
Today, for example, I did two different workouts and used the watch a ton. I was down to about 10% and put it on the charger to top off. The stand metric is the problem here because it's measured in 12hr intervals while on your wrist and, unfortunately, I had to recharge before 12 hours had passed wearing it.
I feel like the watch should be smart enough to allow for charging and saving your tracked activity unless, say, 20 hours have passed since putting it on.