According to their website they typically pay half the down payment (10% of a 20% down payment conventional mortgage) and receive 35% of the appreciation with none of the holding costs, selling costs, transfer costs, etc of real estate. They also will absorb an average of a 35% share of a loss
but that is only (selling price - purchase price) and a variety of other caveats.
Sounds like it could be an excellent investment vehicle for MMMers who want to be involved in real estate without the joys of landlording. Investment side here:
https://www.unisonim.com