Many are concerned - and for a good reason - about the security implications of essentially strapping a surveillance device to the front of your home, but there are many protections in place preventing things from getting dystopian.
We would recommend going for a well-known brand so as not to fall foul of a device that's more vulnerable to hackers, set a strong password when signing up, always download software updates when they are released, and make sure all settings are correct for your needs.
All this said smart doorbells could actually form an essential part of a home security system, adding an affordable camera that can detect motion and send alerts directly to your device when something untoward is going on.