I haven't personally used it, but I've seen places that utilize it (https://www.shopify.com/facebook). I don't know how many people actually buy things directly from social media, since the whole point of social media is to establish connections and have conversations. It could be worth checking out depending on the niche your client is in, but I have my doubts these stores within social platforms are actually profitable.
It looks like it's not too hard to set up within Facebook - https://www.facebook.com/business/news/shopping-on-facebook - so why not explore setting this up in conjunction with a FB ads package for your client instead of having another company run it? Also according to Buzzfeed this seems to be Facebook's next big push - http://www.buzzfeed.com/alexkantrowitz/facebook-takes-big-step-forward-on-commerce-builds-shops-int#.pt12yovez
I'm interested to see if anyone has seen any success with this yet.
