1. I went to the demo page and even though I read the instructions, it still took me longer than it should have to notice the FB stuff. Without instructions and specifically looking for it, I would have never noticed it was there. I guess placement can vary by store design, but the demo would leave me with that worry.
2. From the merchants perspective, I could see the benefits of having users talk about my products on Facebook, but I don't know if distracting a shopper when they are closer to making a decision is worth the trade off. In other words, is the expected value of the links worth the diminished likelihood of purchase? I can't see this increasing the possibility of a sale to the current user. I could be completely wrong and in that case, any data/statistics you could provide merchants would go a long way to convincing them to use Zuupy.
3. To combine 1 & 2 and suggest a potential pivot: As a guy, I am highly unlikely to ever talk about or seek out advice for a general run of the mill purchase. I may seek out the help of, for example, a photographer friend if I'm going to buy a camera, but that may be the extent of it. Maybe I'm just more introverted than others, but going by my FB feed, I've haven't seen it happen much. Judging by the background graphic on you widget, you seem to agree that the target users are women. From my highly unscientific observations of my wife and her friends, they like to show off purchases they are proud of (say they discovered some new fashion and got it at a huge sale). So, what if instead of allowing users to chat with friends before making a purchase and possibly deterring it from occurring, users are presented with a big widget right after the purchase to share and discuss with their friends. You still get the free links plus a stronger social endorsement (this person has just made a purchase) and you don't ruin the conversion funnel. If I was a merchant, I could definitely see myself signing up for something like that (bonus points if it just plugged in to existing shopping carts).