StreetAdvisor is similar to Yelp, in that the content is user generated reviews but instead of businesses, StreetAdvisor has reviews of city neighborhoods. This site would be helpful for real estate investors/ buyers to get a sense of a particular neighborhood or for someone moving to a new area. I was impressed with the quality of the reviews as well, I could tell the reviewers were very thoughtful in their opinions and the reviews were quite thorough to give readers a real feel for a particular neighborhood.  I will say the weak point is that the site mainly has major cities and major streets, so if you're looking for reviews on say, Lancaster, CA, the site won't be as helpful.