We got the camera solely because of the children, for situations where the parents/relatives will be busy, for example cooking or in the bathroom. It's clear that the height of the peephole is not enough for small children to see who is behind the door before opening it. Of course, the screen also helps the elderly, as it is easier to distinguish than the peephole itself, which is a bit blurry if they have vision problems, especially with old doors (depending on the lens). It has a built-in doorbell on the external lens in addition to the house doorbell, the screen response from the moment you press to see takes a few seconds to turn on, the resolution is not the best, but you can see just fine. For the money, it's good! It also has night vision; as we said, the lens is not perfect. If you want better screen and camera quality like a mobile phone, it costs at least twice as much or even more.
Small note: If it's one of the old wooden doors with a narrow peephole diameter, it might be a bit tricky to pass the connection cables to the screen. It's not a big deal, if you're handy you can use a flat screwdriver or a drill to widen it a bit.

It seems for now that it does its job as the camera is really clear in the dark while the presence of the bell is definitely a plus. As a construction, however, I wouldn't call it sturdy in any way, while the double-sided tape it had for the inside of the door sticks only somewhat, resulting in many cases when closing the door it slightly hangs...