To encourage users to share their feedback and improve place pages, Google added a button for uploading photos and made the button for writing reviews more prominent. It's clear that Google Maps will become even more social and will integrate with Google+, so the reviews from your social circles will be more relevant and will help you find a nice restaurant or a fancy hotel.
While Google Hotpot added a lot of new reviews from Google users, there are still many local business that don't have reviews. What's more, the reviews from Google users are usually short, superficial and often they only include a rating.
Search Engine Roundtable speculates that Google removed third-party reviews because of Yelp's complaints. "We are unhappy with the way Google uses our users' review on its Places page. However, there is no solution to the problem… Google's position is that we can take ourselves out of its search index if we don't want them to use our reviews on Places," said Yelp's CEO. After an unsuccessful attempt to acquire Yelp, Google launched Places, Hotpot and made Google Maps results more prominent in the list of Web search results. Yelp felt that its reviews improved a competing service and asked Google to remove Yelp reviews from Google Places. Google decided that it's a good idea to blackmail Yelp and tie the Web search index with the Places reviews (Google News has a different policy and the same goes for Product Search). A such a terrible practice made Google look like a huge company that used its power to crush rising startups.
TechCrunch found that "Yelp made a presentation to a roomful of state attorneys general at the Conference of Western Attorneys General about regulatory issues in search. On that panel was Vince Sollitto, VP of Giverment Affairs for Yelp, along with Dana Wagner, a Google lawyer, and well-known antitrust attorney Gary Reback. Yelp's presentation was titled 'Google Places: A Threat To Innovation and Competition.' The basic argument was that Google strong-armed review websites into providing their content for free, and then gave their own Places product preferential treatment in search."
Instead of removing the reviews from Yelp, Google yanked all third-party reviews and made Google Places less useful. There are still links to other review sites and there's still a small excerpt from a review in the list of search results, but Google Maps is no longer a comprehensive source of reviews, while Bing Maps looks more attractive. Google Maps ratings no longer use data from third-party reviews, but I wouldn't be surprised to see that Google still uses these reviews to rank results.