I live in Atlanta and all of these things are true except that last one. MARTA has neither the coverage or the competence to qualify as 'decent'. Even if they plopped the HQ right on top of Five Points (as is being proposed), most employees are still gonna drive, and encounter that world-class ATL rush hour traffic.
That said, Atlanta is still definitely in play, and our department of economic development (which I used to work for) is one of the most effective in the country. They brought Hollywood to Atlanta already, Amazon shouldn't be that much harder. Culturally, I expect it would encounter a mixed reception.