Contrary to my forebodings (that would stink the envelope possibly after artificial Plstik etc.), this envelope completely odorless and therefore very pleasant. Even open on the table makes it an entirely unremarkable impression that no shell on the iPhone.
Also falls are cushioned - myself, the iPhone is like to work from about 30cm on stone floor and it has gotten no quirks! - This would certainly have been different without (this) Case.
And by the way they naturally also protects the entire back of the iPhone.