I've been using it a lot, actually every time I get in the van
Because of the shape of the jaws and the size/shape of the plastic piece it grips in the dash, the unit droops down. If you drive anywhere it'll bounce up and down.
I cut a piece of plastic, actually an offcut from some plastic garage tile I was thinking about fitting, to stop the unit from bouncing. I cut a letterbox type hole through it with a drill bit, milling drill bit and a file. Didn't take long. Then used a bit of innertube to squeeze in and take up the slack. It was a bit of a trial fit with a plan to do something neater at some point but it's working great so i'll probably just leave it! The other advantage is it spreads the weight of the clamp over a slightly larger area. You can see it in the second photo above.
It's rock solid, doesn't hit my knee and allows me to plug a phone in. Wish I'd had it from the start, it's what I've been after for a while. Also fits a variety of phones which is handy