In its basic functions (as a dumb thermostat), it works correctly. The problems start when you want to use its "smart" features.

I bought it in combination with 7 smart radiator valves, some "smart" plugs, and a few switches. The radiator valves and switches were the only ones that worked perfectly with HomeKit without any issues.

However, this thermostat gave me a lot of trouble in the "smart" part. (Disclaimer: I am a developer, so I know how to debug something). To make a long story short:
- I struggled a lot to integrate it into HomeKit (9 out of 10 attempts failed, with the same parameters)
- I still haven't managed to do it in the Meross app (it is needed for firmware updates)
- I tried to integrate it into the Meross app from an Android device, but again without success. It was even worse there.

But the worst part is that 1-2 times a week, the thermostat would "freeze" in terms of remote management. In its basic function, as a dumb thermostat giving commands to the boiler, it doesn't freeze. It freezes in terms of not responding from the mobile app. So, you have to go to the electrical panel, turn off the corresponding circuit breaker for 5-6 seconds to perform a power cycle.

In retrospect, I saw that many people abroad have many complaints about the firmware of devices from this brand, and many criticize them. Both the thermostat and the plugs I bought have these issues.

To integrate it into HomeKit, what will work easier is to go through the WiFi settings. There you will see that the device has its own WiFi, and when you tap on it, it asks if you want to add the device to HomeKit and your home network.

Apple HomeKit and remote access:
I struggled to make the Meross app work because I couldn't see anything when I was away from home through HomeKit. This was ultimately due to the fact that I had an old 3rd generation Apple TV (which I don't particularly like as a product).
The solution is to get an Apple TV generation 4 or above, or any HomePod. I bought a HomePod mini and now I can control everything in my house remotely.

However, it is useful to integrate the devices into the Meross app for firmware updates and for that reason alone.

IT IS CATEGORIZED WRONG! It is recessed (NOT wall-mounted) and it is also powered by electricity (NOT battery), hence 4 out of 5 ⭐. This issue can be solved with an extra electrical box, but it increases the size of the installation.
Otherwise, very easy to install with a user-friendly menu in the application. It connects very easily with Apple Home.