E-commerce distribution channel experiences a dramatic development nowadays. France witnessed a rapid growth rate of online sales in recent years and now ranks as the second largest market in Europe in terms of turnover. On E-commerce websites, customer review system is considered as an efficient tool of E-Word of Mouth, enabling users to write recommendations which will influence potential purchasers. This paper discusses the crucial factors of customer review system. Also, a tool to evaluate review system is elaborated with five criteria such as accessibility, quality, design, interaction and control. Ten case studies of French E-commerce firms are presented according to those criteria in qualitative study. Opinions from French customers are collected through online questionnaires in quantitative study. Researches made from supply (firms) and demand (customers) sides show that accessibility and quality are the main concerns for users and often weaknesses in current review systems. Also, the credibility of reviews is questioned by customers. Focusing on these aspects, the paper aims to give suggestions for designing an ideal customer review system to firms in French e-commerce industry.