I waited a bit to write this review so I can wear the watch daily for while and get a feel for the operation and accuracy. First off the battery life is amazing. Even with high usage its still really good. I charged mine for the first time after a week of already using it right out of the box. it had 65% charge when I started it up the first time and it still has 25% after a week of use. The different fitness tracking functions work well when they are initiated to do so. what I mean by that is if you just leave the watch on and it tracks your heart rate, spo2, pressure frequently as well as calculating steps, and the calorie burned. there are a lot of workout modes which include things like yoga and simple stretching to more specific workouts. the difference is roughly 4 to 5 times as many calories burned when its in the workout modes vs when not. It should be closer if the watch is still tracking your heart rate and steps and so forth.
Other than that the GPS works pretty well and when it is in a workout mode it seems to have pretty accurate measurements in terms of overall calories burned. I compared it to other fitness trackers that I have used and I think it is more accurate than most in this price bracket. It is a very comfortable watch. light weight and durable. The phone app is neat and the multitude of available watch faces both free and for sale $1 to $2 are awesome. I change mine all the time just for fun. I will continue to use and update this review after a few months.