I recently bought a vivoactive 4s to replace my Fitbit that I've had for years. Yesterday it calculated that I had burnt 3374 calories, 1536 of them being active. All I had done that day is run for 20 minutes (burning 177 calories) and work at my desk. I had a few drinks that night staying up late but mostly sitting down. It had also calculated I had done 20 minutes vigorous excerise (additional to the 20 I did for my run). How and why has it calculated this? I was sitting down!! My Fitbit never gave me these results.
Its only been 3 days and my battery has dropped to 1% (charged it fully when I first got it). And it tracks my sleep when I'm sitting in bed reading a book. It also takes ages for the GPS to work. I have to stand outside for a while before I can start running.
Starting to get concerned as I spent a lot of money on this compared to the Fitbit.