Basically, I am satisfied with the shell. However, she does not sit quite as tight as those Mumbi shell I ordered for my Sony Xperia GO. She sits a little at the top and bottom slightly off (approximately 1 mm). It's bearable, but I have deducted a star. It is very pleasing that the back of the case is matte / rough and not shiny like the Xperia GO. This leaves less dust or other adhering to the shell.
Update: After more than a year, the shell is like new and has no cracks or Abnutungserscheinungen. Top!