Where is the line drawn between being dishonest and trying to bridge the gap between the physical world and the digital world? Where is decoration useful? Where does decoration help the user understand how to interact with the application? When is “flat” too little and “skeuomorphic” too much for the user to figure out how to get his work done?

So, contrary to what the detractors say—there is a place for decoration, and a place for material honesty. These two exist on a continuum, with decoration at one end and material honesty at the other. There’s no precise point at which a design becomes honest or dishonest. The web designer has the messy job of sorting it out.

Material Honesty on the Web by Kevin Goldman