Is this seller finance deal good or bad

[Jorge G.]

Seller has offered to finance his 600k property with the following terms:

10% down payment and 6 percent interest rate. The goal is to wait for rates to go down and me refinance in 3 years for a better rate. The goal of this house is to make it my forever home since it pretty much has all I want in my house. Interest-only payments of 3200 dollars. Looking to do this since my business suffers from seasonality so having the option to only do interest in slower months works better for cashflow reasons. The recession next year scares me and I question if my business will continue to do well. 

Instead of selling my current house which I bought at 214 with a 3.65 interest rate, I want to keep it and rent it out. My current house is valued at 500k so i have equity of roughly 300k.

Is this a good, bad, horrible deal?