It notifies me every time it detects motion, but you need to pay for a server to see who it was.

Very good for its price, notifications come immediately, the batteries last a long time (be careful, they are extra), it has a powerful speaker. The 4 stars are because it doesn't work with Alexa.

Edit 19/10/22: Unfortunately, the free cloud that the company had is no longer available, they want 35 euros per year. It doesn't have an SD card, so if you don't have cloud, you can't see if it has recorded anything.

Well guys, it's really good, I couldn't believe it for its price, and I'm quite picky when it comes to quality issues. Very good image day and night. It works with batteries, but it has a micro USB port on the back if you don't want to use batteries. The charger is not provided. A simple one from a mobile phone will solve the problem (micro USB 5v). Just plug the bell, I mean, into a socket in the house and that's it. In order to receive notifications through the app, talk, and have a video after downloading it (aiwit), you need a good internet signal since it's streaming the transfer of 1080 HD image and sound. I believe no house has such coverage up to the entrance of the house. This can be solved with a simple WiFi extender, a cheap one for 20 euros, where the extender will wirelessly connect to the main router and extend the WiFi towards the bell. Is it worth getting the bell and the extender?
It does the job, and quite well. If the power goes out, if it's working on a charger, or when changing batteries, it retains the settings, as it has a small built-in battery.
I was expecting it with low expectations, but I'm totally satisfied.

P.S. For non-experts, I should mention that you definitely need to have internet on your mobile phone, meaning data, it doesn't make sense to view it through the WiFi of the house.

Easy installation
Very good image
Powerful speaker and good microphone
The voice from the mobile to the doorbell sometimes has gaps, maybe due to low internet signal strength.
The internet notification has a delay of about 3-4 seconds.
The doorbell has an immediate response.
It can be installed on multiple devices.
It requires 2 18650 batteries with the positive pole protruding.
The battery life depends on 3 factors (battery capacity, frequency of use, and internet signal strength)
I have installed 2 3000mah batteries from Panasonic with poor to fair internet signal and low usage, it is at 43% after 2 months of use.
The camera opens without pressing the button beforehand.

P.S. I haven't set up motion notifications... important