According to a recent study about local ranking factors by Bizible.com, having five or more Google reviews was associated with a 1.85 improvement in rank in pure local results. Bizible also discovered that not having any Google reviews on your Places page or having an average review score of one hurt rankings.
The fifth Google review helped rankings significantly, however incremental reviews between one and four and above five had very little effect on rankings. After the fifth review, it is likely that you would have to get 100+ reviews to make another significant impact on your ranking. However, this study goes to show how important it is to encourage your customers to leave positive reviews on your Google Places page.
Need help getting customers to review your business? Check out Get Business Reviews, a section of our Local Splash website dedicated to educating business owners about the importance of business reviews, how to get reviews and how to deal with negative reviews.