I like it. It would be something I could see myself using, but I don't see myself taking the time to set it up. In your early experiments, who did you discover your target market to be. Remember signing up isn't enough of a hurdle to really determine your target market.

My first thought is, I don't see the pricing page. To me this is a service a marketing department or agency would use. That being said I don't think being free is the right choice.

I would try to find a few agencies who manage social media campaigns and a few social media managers for a brand. Set your price, help them setup their account and keep in close contact with them. Kind of a modified concierge MVP. I would not got free for them. Make sure they have some skin in the game, so they will give you honest feedback, and have more incentive to collect ROI from the service.