Should I spend money on Yelp/Yelp Ads?

In 90% of cases, no you should not be advertising with Yelp. When compared to spending your ad budget on networks like Facebook or Google, Yelp has shown a significantly higher cost per lead. For our larger clients who are already close to "maxed out" on other major networks, AND who already have a good presence on Yelp (100+ reviews), Yelp then becomes a viable option as a cherry on top, not as the foundation of the cake.