I am not real sure about this, but you may want to check on the legalities of posting negative reviews or allowing members to post negative reviews. It is probably not a big deal, but I would hate to see anyone get in trouble or the site get caught up in some ridiculous lawsuit.
This one is pretty easy to get around, and all it usually takes is a really well written Terms of Service. I know this from experience in the e-tail industry, and a carefully worded and well thought out Terms of Service can keep a site/business out of really hot water. Even though people can threaten to sue up one end and right back down the other, if you point out that you, as a site admin, are not liable due to the fact that they agreed you would not be held liable in the case of disputes, most people who are puffed up tend to deflate when they realize there is nothing they can do against the site.
Seriously, I had someone who worked for the Justice Department threaten to sue my former company for a piece of information their mother agreed would be kept on file, and when I showed her where in the TOS she had no grounds to sue, her attitude switched from aggressive to apologetic. Phrase it well, cover all bases, and unless there is straight up slander or defamation of character involved, the admin is pretty safe from legal harm.
PM me if you'd like further details KyleT, be more than happy to share what I know of the subject.