A review is a buyer’s guide. It exists to tell you about some new product that you can buy, and whether you should or should not buy it. A good review goes beyond that, and suggests who should buy it, since not everyone enjoys everything. [...]
Criticism is an informed discussion, by an intelligent and knowledgeable observer of a medium, of the merits and importance (or lack thereof) of a particular work. Criticism isn’t intended to help the reader decide whether or not to plunk down money on something; some readers’ purchase decisions may be influenced, but guiding their decisions is not the purpose of the critical work. Criticism is, in a sense merely “writing about” — about art, about dance, about theater, about writing, about a game–about any particular work of art. How a critical piece addresses a work, and what approach it takes, may vary widely from critic to critic, and from work to work. There are, in fact, many valid critical approaches to a work, and at any given time, a critique may adopt only one, or several of them.
Some valid critical approaches? Where does this work fall, in terms of the historical evolution of its medium. How does this work fit into the creator’s previous ouevres, and what does it say about his or her continuing evolution as an artist. What novel techniques does this work introduce, or how does it use previously known techniques to create a novel and impactful effect. How does it compare to other works with similar ambitions or themes. What was the creator attempting to do, and how well or poorly did he achieve his ambitions. What emotions or thoughts does it induce in those exposed to the work, and is the net effect enlightening or incoherent. What is the political subtext of the work, and what does it say about gender relationships/current political issues/the nature-nurture debate, or about any other particular intellectual question (whether that question is a particular hobby-horse of the reviewer, or inherently raised by the work in question).
Greg Costikiyan. “Game Criticism, Why We Need It, and Why Reviews Aren’t It.” Play This Thing (24 Feb 2008). (link from Mark Bernstein.)
Costikiyan is talking about game criticism, but for the most part his comments could be applied to any medium, like comics.