I have one of the HF versions of that cart - which sells for less than half the price - less than a third when it's on sale, which is often... I use it for bringing in firewood in the winter, and moving splits and rounds as needed in the summer. It does go up stairs and obstacles quite well, but it won't help much if you have a bad back as it still takes quite a bit of effort to get the loaded cart up the stairs - however a cart load is a LOT more than one could hand carry...
That said, I have a couple of comments on the HF cart that will help make it last better...
1. The tubes are cheap, and tend to do the slow leak. Don't bother trying to patch them if / when you get a hole in them, as they will just split. Get a pair of replacements at Walmart, or if feeling rich, the local bike shop - much better quality...
2. Before putting the cart in service, pull the tires off the wheels and take them to the local pedal bike shop, get them trued and the spokes tightened - otherwise they can develop a bad wobble and collapse, trashing the wheel - replacements are more expensive than a new cart! (ask how I know...) Also get the spoke heads inside the rims ground, I had several where the spoke was close to poking through, which will do in the tube in a hurry...
Gooserider