Things might have changed but my brother in NYC soon after getting his 4 was getting in the 4 Mbps range. Upper east side.
Here in FL I average 2500-3000 Kbps lately, but it's not unusual to get over 4000 Kbps. Best ever was well over 5 Mbps. Upload seems more consistent, usually about 1250 Kbps. I have to admit AT&T has really sped up in the last 6 months. Before that, it was typically 1200 Kbps, with 2000 being max, and peak times were around 500-800 Kbps.