Do a trial of the service first to see if it meets your needs. We were very early adopters, so have seen the program grow and expand over the past couple years. The Reviewbox team is adding features based on customer interests and needs. The web interface is not the smoothest, but I value that they are putting more resources to growing the capabilities over aesthetics.
In addition to the basic review and question monitoring, they have some other programs worth investigating. Their value will depend on what kind of seller you are (1P vs 3P, # SKUs) and access to questions is really only valuable if you intend to answer them! Review collected by and hosted on G2.com.