Along with the recent rollout of Hotpot, Google has added new review related features to the Places Page. The first, available on restaurants and hotels (perhap more but not on every type of business) allows you to summarize sentiment about the location:
The ability to quickly and easily add sentiment will further build out Google’s data in the service industries. As users fill out more reviews, friends make more recomendations Google will use this additional data to refine and improve those recommendations.
This feature facilitates the process of getting bookings and removes friction from it. It also provides additional advertising inventory for Google from hotel booking services. The feature is not totally mercenary as it also offers up the hotel site for booking and gives the hotel a 1 in 4 chance of not having to give money to Priceline et al while still getting a sale.