Once of the questions I get most often is: between Facebook Ads and Google AdWords, where should I be advertising, and why? It wasn't until recently that many advertisers viewed Google AdWords and Facebook Ads as efforts that couldn't get along. Water and oil. But when it comes right down to it, they compliment each other when you have, and implement, the right strategy.
Each have their own pros and cons to be sure, but they cannot be ignore and need to be working for you. You need to be touching with your audience on a regular basis and advertising is a very effective way to stay relevant (by showing up consistently in ads) and increase brand awareness.
Back in the good ole' days you could post to Facebook (without advertising on Facebook) and increase your Facebook follower base at the same time because more people would see your organic posts, "share" them, "like" them, "comment" on them and thus more people would ultimately see those actions - and see the brand name behind the interaction. Those days are over and pretty much everywhere you go these days, its pay to play. You know this.
Advertising on Google is a no-brainer, but do I need to be advertising on Facebook too? Yes. They best short explanation I've ever heard comes from a post via WordStream, which explains that "AdWords helps you find NEW customers, while Facebook helps new customers find YOU." Everything I have experienced validates that statement and it helps me approach each medium with a different approach.
Checkout the rest of this great post via WordStream which provides some great additional information on this topic -> http://buff.ly/1U3IO83