A good review is money in the bank.  A bad review can be a problem.  Review sites will work with you if there is a bad review that is unfair.  Lets say a competitor wanted to hurt your business to drive customers to his business.  A series of bad reviews could be the method employed.  Sometimes according to sources a business is doing its best to service its customers and is oblivious to how the review sites work.  If you want a good result you have to be on top of these technologies. Stay aware and you will be able to turn these reviews into positive business results.