For an article review your task is to identify, summarize, and evaluate the ideas and information the author has presented. You are being asked to make judgments, positive or negative, about the content of the article. The criteria you follow to do this will vary based upon your particular academic discipline and the parameters of your assignment.
Your evaluation must go beyond a "gut reaction" to the work and be based on your knowledge of the topic (gained through readings, lectures, and class experience) as well as on what you learn through additional research. Writing the critical review requires you to read the selected article in detail and other related articles so you can present an objective and educated evaluation.