Here's a video of someone running a bandwidth speed test via an HTC Jetstream tablet connected to AT&T's nascent LTE network. If these speeds hold up, well, we're in for a treat.
As you can see, the download speeds peak at over 22Mbps, with upload speeds hitting 6Mbps. These speeds are comparable to a decent cable connection, meaning you'll have broadband speeds in your pocket. Not too bad!
Of course, once there are thousands of people all downloading at the same time speeds might suffer. And with AT&T's tiered pricing plans for data, you'll pay dearly to download anything of substance using these speeds. But still, it's nice to see that the infrastructure they're building out looks to be solid.