How (Super) Rough is the Glassy Phase of a Crystalline Surface with a Disordered Substrate?

We discuss the behavior of a crystalline surface with a disordered substrate. We focus on the possible existence of a {\em super-rough} glassy phase, with height-height correlation functions which vary as the square logarithm of the distance. With numerical simulations we establish the presence of such a behavior, that does not seem to be connected to finite size effects. We comment on the variational approach, and suggest that a more general extension of the method could be needed to explain fully the behavior of the model.