Fitness features: Health-monitoring functions that take advantage of a watch’s sensors should be easy to use and actionable, and they should protect your privacy.Battery: Smartwatches should last a full day (at least 16 to 18 hours), so your phone and watch can go on the charger at the same time.If you have to wait on a watch to check your notifications or heart rate, it’s not worth using. Performance: Smartwatches that lag can end up being less convenient than your phone.Notifications: A smartwatch should mirror notifications from your phone quickly, making it easy for you to dismiss them or reply in a couple of taps.
