In the cold weather, it was open all day and kept a large room with poor insulation at satisfactory temperature levels.

In the negatives:
It does not save the weekly program if it goes out of power, so the whole function becomes useless.

In the positives:
The highest quality construction I have seen in this category. They say that a device is judged by its cable. This particular one does not have a simple PVC cable but a fire-resistant silicone one.
Because it was installed in a bedroom, I opened it to check internally. High-quality silicone cables and the thermostat cable is fiberglass insulated. The resistor is not a simple "naked" resistor that can ignite if dust accumulates or if a child puts something conductive, there is a risk of electric shock. On the contrary, it has a PTC (ceramic) type resistor, which due to its increased surface area, there is no risk of ignition in case of dust, while it is not electrically conductive (the surface).

Also, in the positives, the air vent is on the sides and not on top, so it does not accumulate dust inside for safety reasons.

If you have space, it would be better to get the 1800-watt version. In terms of power consumption, they will consume the same amount of electricity given that the 1800-watt one will reach the desired temperature faster and the thermostat will turn off faster.

Finally, for those referring to the heating capacity of air heaters - radiators, etc: They all have the same efficiency, which involves almost 100% conversion of consumed energy into heat unless you find a product that walks around the house, then there will be a percentage converted into kinetic energy. To achieve higher efficiency, you need to switch to a heat exchange method, such as a heat pump - air conditioner, which provide over 200% efficiency.