When does it make sense for Seller Financing?

[Craig Simak]

I'm in negotiations on a duplex here on Long Island that I can purchase for $425,000 and collect $4,500 gross per month with minimal Capex. The seller seems open to financing with 25% down but I'm wondering what the advantages are to me when I can get a 30 year mortgage at 3.69% from my community bank with the same or less down.

Please enlighten me on why so many investors brag and salivate over seller financing.