When it works it's good but it is a constant pain in the morning trying to sync the overnight data. It only does it correctly occasionally. The rest of the time is spent closing down the app, switching Bluetooth on and off, restarting the app and the device, trying to make it sync. And then it still doesn't!! I have to enter my sleep manually and then mostly it will work out the rest of the data. I have premium free as I upgraded from Alta HR to Charge 5 at Christmas, but I shall be cancelling!