I noticed the same here (Chicago area) already in WP7.5 on my Lumia 710 with Nokia Maps, which is the only maps app on the Lumia 920 (correct me if I am wrong and please dont quote Att Navigator
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). However if I used Bing Maps, the traffic info was way more exhaustive than with Nokia Maps. Doesn't seem to make any sense.
I had an issue with my Lumia 920 this morning, where it would register the Att LTE service and immediately disconnect again striked-through 5bars, then reconnect and disconnect...
After I turned on Airplane mode and then off again, it worked fine.
Coming from a Lumia 710, the Audio quality on headphones is superb on the 920, even podcasts sound great like you are in the Studio
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(with Klipsch S4i)