Coverage is spotty. I live close to Discover Mills and I can get a strong 4G signal in my house (avg 20 Mbps with 32 being the highest). If I go a half of mile away from my house in any direction..back on 3G.
I work in Sandy Springs at 285/400 and can get a 4G decent signal in my office (avg about 6 Mbps). But I was only getting 3G at the intersection of Hammond Dr and Peachtree Dunwoody.
Maybe I'm really lucky to get it both at home and at work (although I use wifi at both so I don't really need it).