Pros
From edgy start-up to one of the coolest companies in tech, Yelp is owning the local search scene around the world making the job WAY easier as time went on - the product/company had a lot more name recognition by the time I left compared to when I started. Culture is awesome, people are awesome, beers are on tap, kitchens stocked with food (not just snacks, you can literally eat breakfast and lunch there), and everyone generally wants to succeed and have a good time. It's hard not to get into it, especially considering you're selling an app that's actually pretty fun and was originally geared toward interesting people who go out a lot. The difference is that people (biz owners and consumers) have a real need for this kinda stuff, so I always felt great about selling it.
Cons
The company is growing aggressively - from just a couple floors when I started to 4 additional floors and a brand new office waiting to get moved into by the time I left, the place definitely churns people in and out. Not necessarily a bad thing but they may want to slow the growth down a bit and concentrate on hiring stellar reps who retain the company culture instead of a bunch of mass hires and clueless drones walking around.