Does anyone know about the reliabilty of a goodman gas furnace and ac unit?

They work OK BUT a piece of equipment is only as good as the install.

I personally have had great luck with them, very few call backs. But like HVAC1000 says, install is key. Most all furnaces and ac units on the market today are good, some have more bells and whistles, but bang for the buck, Goodman, with correct install is a very good product. I would be more interested in how dependable the installer is to come back and fix problems (should they occur) in a timely manner, especially while unit is still under warranty.