The rubber absorbs shocks to the lens, thereby protecting against small misfortunes. (You should not expect miracles, of course ...)
Unpleasant odors, as they often occur in rubber times, I did not notice.
The lens cap fits on the filter thread of the lens hood. This one always goes down well the lens cap, even if he has to unlock snapper on the side. That's when the hard plastic lens hoods often very difficult, as too tight and also the main reason why I prefer rubber against hard plastic case lens hoods.
With the Olympus M.Zuiko Digital ED (12-50mm 1: 3.5-6.3 EZ) lens I've found below about 16mm focal length (32 mm KB-equivalent) a significant vignetting (shading of border areas). From about 13mm can be seen only through a circular hole ...
I find the lens hood excellent (therefore also 5 star) only for use with wide-angle lenses, it is not suitable. For larger focal lengths a strong buy recommendation.
