Wonderfully sturdy. The wheels on this one (stairs) are slightly smaller round than the cart we replaced. Not sure how that will/not affect use. TBD So you screw on the tiny wheels under the platform. They move nicely, very easily, maybe a little too much but can that be a problem? Well yes, if the cart is still empty and you're holding a heavy box and the cart is moving when you try to aim the box at it (without eventually dead-dropping a heavy box onto the platform (that it could break). So you tilt the cart, once all is on it, and you're heading out. You arrive and unload your boxes, you reach around toward your empty hand truck, and (because the platform is now empty) in an instant your ankle is hit by a moving platform that \"folds flat\" just a bit too easy. I am being just a touch dramatic for time-sake there, but it hurt my ankle, when the platform by-design folded up all by itself, seconds after it no longer had any boxes on it. By design I mean, it is intended to fold flat, quickly. And it does that well: It is sturdy and well made (which made it hurt that much more as the platform hit my ankle bone and hard). What this cart is missing is a wheel/platform lock of any kind, on the platform to lock it open even when empty, and on either set of wheels (which roll wonderfully - and keep rolling away from you as you try to load/unload it). So: 4 stars, 1 star off for no locking mechanism at all on both the platform wheels, the platform, and the stair wheels. Does it do what the ad promises? Yes it does. Is it made well? Sure is, good materials (so far my experience). I appreciate that this can move heavy stuff for me, up stairs, I really do. NOTE: This would be a 10-star review had it not been for not having any wheel lock. To be clear: Item as promised in ad thus far.