Slippy, narrow straps that don't stay on. Cushioned by thin pads that don't stay in one place and so fail to cushion anything.
Front wheels that swivel when you go too fast - phoned about that one and they sent some sticky pads to solve the issue. Until the pads wear through. Lucky they sent three sets, then. 
And then just after the pads arrived, the mechanism that allows the user to raise and lower the handle broke. Cue the handle ratcheting up and down every five seconds, mostly defaulting to the lowest setting and killing my back.
I rang them about that too but apparently it's not a fault so I needed to go through the retailer. Shame we've moved 100 miles since we bought it. I tried rigging with duct tape but surprisingly my bodge job didn't last long. What a load of expensive tat. And it's killing my back.