I bought it for professional use to transport cardboard boxes. If the box is up to 40cm, it does the job carrying up to 3 boxes at a time. But if the cardboard boxes are bigger, they fall off and you can't transport them as it has a relatively small base. With boxes that fit, it goes up stairs incredibly easily as long as the load is not over 80 kilos. Once I put a load of about 100 kilos on it, that is, half of what the specifications say, and on a flat surface everything was fine. When I tried to go up a step, no way. I couldn't do it at all and I'm 1.98m and 95 kilos body weight.
For simple use, it's just right. For professional use, only for small cardboard boxes unless you improvise with a strap. For me, its use has ended up being to carry firewood from the garden into the house. At least that's something. Finally, I should mention that assembly is super easy as you only have to attach the wheels.

It is heavy construction, so theoretically it is good. The wheels on the stairs do work, but they require a little more force to roll. Overall, it requires strength in handling, but it remains very useful.