Everyone in RG has been at least an author or reviewer or both. And, because of this simple fact, everyone has their own experience with the reviews made on their own papers by others or the reviews the others have made on the papers of other ones. However, the quality of a review, which is both a process and its result held to be of crucial importance for the reputation of every conference, journal, or publisher, is not still a clear concept, while its elements are less than clear both in category/kind, quantity, label, interrelations, etc., although the elements of a paper's manuscript are more easily captured.
I invite everyone interested in giving their own experience and opinion about what the elements or criteria for an excellent review may be. I think that this discussion may be of much help for the research efforts and scientific quest of everyone towards excellence by being engaged in a spending of their own time, energy, and money, and often charged by a non-negligible stress and incredulity.