Disadvantage: one does not feel the many different surfaces (sand, Moon, Mars, grass ...)
Advantage: the fingers remain clean. Well, if it rains to deal with the children. I've been using it very much as a note, male sketches, hold on ideas, using it as a Zen (?) Garden and thus create small cards (and send them by mail or equal Socials).
Had the free version and wanted to have unlimited fun. Do I have. With sea view or without, of the sun and therefore the atmosphere may be adjusted with finger, many different colors, islands and beachcombing let countless combinations arise and it is easy to save and delete funny.