I use RV park reviews quite often. You do have to read the reviews carefully to make sure what the reviewer values highly is in line with your own desires. Example: Recent reviews of a park got high marks for the great facilities for young kids. That did not play highly with me. You should also look carefully at the park's web site. I am always skeptical if they don't have any pictures of the actual RV sites.
Basically, what I'm saying is the RV park reviews can be a useful tool, but should be used with some discretion. I do post reviews on the site and try to be as honest, fair and specific as possible.