Significantly better than expected, great!

Did the shell now since a few days and have to say: great!
The shell budge, wobbles as jerky and nothing. It has rather little trouble, abzubekommen the envelope again ;-)
The shell can be free all controls, and the flash is not affected while taking pictures.
The front side is protected, since the shell can withstand minimal also at the front. That is: even if you put the Lumia on a smooth surface (eg table) to the front (for whatever reason), it is no longer on the glass, but also the shell. Prima!
The "problem area" of the 820, which easily scratchable objective environment (ie the aluminum part where Carl Zeiss is) is optimally protected.

The material is hard plastic, the back feels very slightly "rubberized", is therefore very slightly roughened and gives a very good impression and prevents slipping in the hand.

For the price (at just under 7 Euro incl. Postage) highly recommended! Draufmachen, is good.