Has anyone applied for the Market Place 2018 (Obama) health care insurance or had it before?

Wanting to get some info on the market place (obama) health insurance for 2018 that my time to apply is running out soon.
Living on a farm we have plenty of deductions and not making much money right now…just 2 of us. I have heard pros and cons. You have to estimate for next year based on the past year I believe. My friend’s friend had it last year and ended up owing money. Is it worth the time to look into it…anyone know how it really works?