I updated last night. Speeds prior to the update were not so great. I have H+ showing and before the update my download speeds were in the 1.5-2.5 Mbps range. Upload speeds were 0.3-0.5 Mbps. After the update, the speed are MUCH worse. I can't get over 0.2 Mbps down. I pulled the battery 3 times. Restarted the phone, left it off over night, pulled the battery again,restarted the phone. Currently speedtest with 4 bars showing H+ I am getting 0.12 Mbps down and 0.11 Mbps up with 221 ping.
I've only had the phone a week, its pretty impressive, but ATT service appears to be a joke.