Techniques are described for assessing information supplied by users in various ways, such as to assess the reliability and/or other attributes of the user-supplied information. In at least some situations, the user-supplied information includes votes or other evaluations supplied by users related to items available from an online merchant, such as ratings of usefulness or other attributes of item reviews for the items or of other types of content pieces that are provided by other users. If user-supplied information is assessed as being sufficiently reliable and/or to have other desired attributes of interest, such as based on an automated analysis of the information, the user-supplied information may be used in various ways in various embodiments, such as to rate the quality or other attributes of the evaluated content pieces, and/or to rate quality or other attributes of the content-providing users who provide the content pieces.