On the basis of the data from ground-based polarimetric, photometric, and other observations, as well as from space measurements (Mariner 10), we survey the investigations of the properties and peculiarities of Mercury's regolith in detail. We also present the results of our own observations performed during three apparitions of the planet in 2000-2002. An analysis of the published data points to essentially more intensive maturation processes in the Hermean surface regolith compared to that on the lunar surface. In addition, the orbital characteristics of Mercury allow us to suppose that the intensity of its regolith maturation and, therefore, the optical properties of its surface can noticeably depend on the planetocentric longitude. Polarimetric observations of Mercury's surface (the planetocentric longitude range was 265°-330°) carried out in 2000-2002 with a 70-cm reflector actually detected a polarization degree varying with an amplitude of about 1.5%. To ascertain the nature of these variations, additional observations of Mercury in a maximally wide range of planetocentric longitudes of the viewed surface are required.