Its not really new, I've had one since last year. Great little toy for under $200. Battery is great, lasted me 22 days last month, this charge was 10 days ago and still at 67%. Yes it does sleep tracking. It also has a display with time, a function the previous model did not have. It also vibrates when you get a whatsapp, sms, voice call, and other things you can customise. It's generally quite cool but sometimes my wife or whoever will send me a bunch of whatsapps and I want to rip the bloody thing off my arm it keeps vibrating every few seconds.
The Mi scale is also pretty good and well built, looks very sleek solid heavy white glass and also under $200. It integrates with the same Mi app for ios/android as the band and automatically recognises different members of the family.