It's great going up stairs; heavy loads take a fraction of the effort of a normal hand cart, light loads take no effort at all.
One objection to it is that the wheels sit forward of the back brace, so unless your box is narrow enough to fit between them, it has to sit forward on the cart by about three inches...definitely need some bungees to keep things from slipping off.
My main complaint is that the wheels don't lock in place. The instructions say they are supposed to snap and lock in place but they don't. If you tilt it forward the slightest bit, that puts pressure at an angle on the front support plate...which is how you are supposed to fold it up. Tilt forward, wheels fold up. Very annoying to have to constantly kick the wheels back out to keep everything from collapsing. That's a real problem for me because the supposedly easy open/easy fold-up was one of the main reasons I bought this brand.
Also, the button to extend and retract the handle is very stiff; I need both thumbs and a lot of pressure to activate it. I've got arthritic hands, so it's not easy.
When you DO want it to fold up and get stored away it does make a nice flat, compact package.
If I'd had a chance to try it out first, I'd have looked for another brand, but stores don't have things in stock anymore, right? It's all stock in a warehouse somewhere that you order on a website and have sent to the store for pickup; no chance to take measurements they don't include in the specs, no chance to see if it handles well for you.