Seller finance to investors

I am selling an brand new house, but stuck for some time because the neighborhood is not very good but I am asking for 700k for the house. It's about 3000sf. So now the situation is it's not easy to neither sell nor rent for more than 1 year. Now someone (likely an investor) offered a seller finance with 350k down payment, and offered above listing price. Looks tempting, but is there any catch with seller finance? Also I am wondering how this investor may benefit from this sell because I am being stuck for more than one year now. Thanks.