Yelp is HUGE, and I get a LOT of customers from them. However, I do not like they're paid advertising setup.
1) The fact that they want you on a contract shows that they have very little faith in that they're ads actually drive you more customers. Google, facebook and other advertising streams allow the user to adjust daily spending limits at any time, and to cancel at anytime
2) Its basically a pay per impression based system. Meaning that if you spend $325/month and it includes 500 impressions, that everytime your ad appears on someones search, you're paying for it out of your allotment. which brings me to the next points:
3) You cannot control your keywords, location, and demographics for your ad. If you search for your business category on your yelp app, other related businesses ads will appear frequently.. such as glass repair, or body shop. Which means that when someone is searching for glass repair or body shop, your ad might also pop up.. which comes out of your impressions but isnt directly targeting your potential customers. Yelp wont let you fine tune your keywords at all.
3) Impression rates vary based on availability and demand, but there's no way to know when rates may go up or down. For example, if your're paying $325/month you may get 500 impressions one month, but next month when they sign up a few more competing businesses, you may only get 400 impressions because now there's more competition for those searches and they need to fill them with ads. At least with google and FB you can see the current rate for clicks or impressions, and set a daily budget. The more businesses they sign up, the more competition for ads, the more they charge, the less you get.
4) There's no guarantee that your competition isnt searching your ads and using up your impressions. Yelp doesn't give really any use able information and statistics about who is viewing your ads and business. Google has an algorithm that wont charge you for multiple clicks from the same IP. Not sure about FB.
5) This will vary. But normally we are averaging about 400 views a month on our yelp page, when we did yelp advertising at $325/month we saw a rough 10% increase in views. So basically we paid $325 a month to get 40 more views, of which if 50% used our services we paid $16 per customer.
Benefits of Yelp ads: No competitor ads on your page, better photo structuring of your business.
And to end this rant, i HATE YELP. I got awesome reviews so I cant complain, but their review filter is garbage. Some businesses have no filtered reviews while others have all their reviews filtered. I notice that businesses that seem not to care about, or view their yelp often have less filtered reviews than ones that are constantly checking their reviews like me. I have 25 public reviews, 7 filtered. A neighboring unrelated business that does not manage their yelp page has over 100 reviews and only 4 filtered. It is most definitely biased in some way.
. Busy day I've seen a million uniques an hour. Seriously? 400 views is a pittance. You're better off on Facebook or Twitter for free. 
