I ordered about 5 'skins' for my 820, 'cos there aren't many available in shops. I was looking for mechanical protection, plus something to make it feel less likely to slip out of my hand. So far, this one is the best. Actually, it looks that good that I almost feel like dropping my phone on the floor to test it. I won't, but, if you are looking for a skin for mechanical protection, this one is good. The screen cannot be contacted when face-down on a flat surface. The corners are very well buffered. The styling is discreetly strong. It is a good bit of kit for an 820, in my view.
It is a little fiddly to affix. Do the rubber bit first. Then add the smaller backshell. It then needs a bit of manipulation to get it settled in the right place. Once it is there it makes the 820 feel rather robust.