I would actually say that yes, Yelp converts very well for small businesses.

Recently, when I was looking for a printing shop to print my wedding invitations, I was very highly intent on giving someone my business. Out of the 4 printers I researched on Yelp, I picked one and paid for that company's services.

Generally, people browsing Yelp have a very specific goal. They're searching for a business to use and ready to choose and pay.