Is buying a lease-to-own contract a good idea?

[Rolly Dupree]

I am thinking about buying a property which is leased-to-own for the term of 6 years. The numbers look like this:
Purchase price : $15k
Rents: $450/mo after taxes & insurance
At the end of 6 years the tenant owns the house free & clear and I have received a 20% ROI.
Does anyone think this is a good deal? It does not feel right, because I won't own the house after the 6 yrs term.
Thanks for your help, Rolly