Strictly speaking, Shino is a rather simple glaze. Composed of mostly feldspar and ash in Japan and of nepheline syenite and spodumene in the West; the bulk of the formulas are just a small handful of materials. It would seem that the proportions of the materials and those "secret ingredients" makes all the difference from glaze to glaze and potter to potter. Secret ingredients aside, there are other such variables like type of clay body, quality of slip or washes and of course how the pots are fired, wood fired being among the finest, that can really make a Shino glaze stand out. I guess in the end, there is no such thing as simple Shino.
Simple glaze plus simple chawan equals, masterpiece. Illustrated is a wonderful Aka-Shino chawan by the father of modern Shino, Arakawa Toyozo. Using a fine traditional mogusa clay, this chawan was wood fired to produce a bowl reminiscent of some of those Momoyama masterpieces.