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Works great!
Decent intensity and color performance (okay, it's not Phillips Hue) and
no issues with disconnections (it was placed quite far from the router, with 2 walls in between and under the bed).
Connects via wifi or Bluetooth as well as IR remote control.

The first 433.92 MHz switch that I tried doesn't work with Sonoff RF... so it was left aside.

To change the battery, you have to unscrew the back... so even if it worked, you would have to detach it from the wall every time.
Also, it only fits with double-sided tape (not included), you can't screw it to the wall because the screws of the back catch onto the frame.

Connected for 1.5 years, no disconnections and works seamlessly with A/C, TV & home cinema... I have also connected the cable with the thermometer.
(Except for a small period of 10-15 days when it received a faulty update and messed up the A/C settings).

Combined with the Sonoff temperature sensor, the connection is constantly lost (regardless of distance). If you unplug it from the socket, it finds the sensor again... and after 1-2 days, it starts all over again.

compact and seems to be well made.

it is very slow (I didn't notice that it is only 1000w).
For 800ml of water it takes 6 minutes ... the 15-year-old primo 2000w that was replaced took 2.5 minutes ... measured side by side.

It does what it says ... 2 months without any disconnection, no problem, very easy installation and pairing with the switch.

It shows a temperature 0.5 degrees Celsius higher than a conventional thermometer.

You can use it as a trigger in scenes on eWelink.
Alexa does NOT see it as a trigger.

Edit after 2 months... it constantly disconnects!!
I do not recommend it (even though I am a fan of Sonoff).