The system is good but slow to respond. I think this is pretty typical of this type of device. Ours is hard-wired (no WiFi). The only problem has been the illumination light cover, which ham-fisted delivery people tend to crunch, rather than pressing the call button. The covers are not particularly easy to replace and are not cheap.
Love it!!! I previously had the wall mounted version and I wanted the cleaner look of a flush mounted doorbell. It looks great and I prefer DoorBird over the other video doorbell options as it is hardwired and is an active camera.