There are 2 different ways to "rent to own"
One is a lease/option,
The second is a lease/purchase
The biggest difference between the two is that with a lease option, you have the OPTION to purchase at the end of your lease term.
With a lease purchase, you must purchase the home.
The leases are written up differently.
One of the downfalls can be for a tenant, that in a down market (check to see what your specific local market is doing and where the predictions are as to where it is going) by the time you purchase, the house may not be worth the price you set when you signed the lease. Therefore, the bank will not loan you the $$$.