What's the catch?

The honest answer: If your home gains a lot of value during the agreement, Unison's share of that appreciation can exceed the total interest you might have paid on a loan. That's the trade-off. Cash now with zero payments for up to 30 years in exchange for a slice of the unknown future growth in your home's value. If your home doesn’t appreciate that much, or even loses value, equity sharing can be a significantly more affordable way to access the wealth in your home.