They are just promoting the idea right now not the product. There is no detail about globalcoin at all, hell even the name could be changed eventually, however there is just one thing for certain, facebook is starting a crypto currency of their own. That information is legit and it will happen unless they cancel it, I mean that is still possible but aside from that they will definitely have a crypto currency.
How it will be used, what it will be used for, how many supply total, what the starting price will be all haven't been decided yet, as we get more information about it we will be able to give more opinions and healthier opinions however as long as we do not have any details all we say will be just assumptions. I hate facebook and how they run the company so I will say bad things but we still need to wait and see.