I bought 2 devices, one for the sink and one for the kitchen. The way it works after being connected is as follows: it only provides cold water, if you want hot water, you turn it to hot without being able to choose the temperature. Empirically, if you turn it to the maximum hot setting, then the water temperature is good and you won't get burned. This happens because fully opening the supply increases the flow and the water doesn't have time to heat up. If you have the supply slightly open, it is possible for the water to burn because it stays longer in the heating element. As an idea, it is excellent because you don't draw any water from the solar water heater (I noticed a noticeable difference) and you have instant hot water without waiting. Let's move on to the negatives: in the first few days, the power plug melted without me realizing why... possible failure in a cheap converter... I replaced it and it continued to work... after 1 month of use, for unknown reasons, it had an internal explosion (not during use), the power went out and water started spraying from the switch... the same thing happened with the sink device, but without an explosion... I do not recommend it for any reason! Now, some people who have given it excellent ratings either have it for a very short period of time or they are selling it and want high ratings...

The quality is average. It's all made of plastic.
The instructions are lacking (almost non-existent).
It consistently consumes 3000W and depending on the water flow, it reaches the corresponding temperature (with a high flow of icy cold water, it barely reaches 22 degrees, while with low flow it reaches 30-32 degrees).
It splashes a lot (but this is relative to each person).
The positions that the selector can take are: |Maximum to minimum hot flow| Empty space with no water running| Minimum to maximum cold flow| (more details in a video on the internet)
When it operates with cold water, it doesn't consume any electricity.

Edit: After ~8 months of use (only the first 3 connected to the power, as we didn't need hot water for longer), it started dripping from the hot-cold selector handle.
The build quality is very mediocre.
For a vacation home or a space where it's not worth installing hot water pipes (or if it's not possible), it's fine (as long as it's used 2-3 times/month).
For more frequent use (e.g. I had it in the kitchen), something of better quality is needed.