My 4G was great the first few months I had the phone (I'm in Atlanta area), but once they started rolling out LTE all over the place it went downhill. I've had 4G outages and slowdowns on a regular basis the last couple of months.
For the record, no problem here in Birmingham, AL. Still getting good speeds (8-20 down depending on test server selected). For those experiencing issues, have you tried the cursory battery and SIM card pull for five minutes to reset the phone and force a reprovision on the network?