In my case, the browser wouldn't work, so I thought I wasn't getting 3G. But the status icon indicated a connection to 3G/3.5G, and I was getting data thru other apps (MfE, RSS feeder, etc.) and I couldn't find any settings in the browser that addressed it. I flashed the firmware and the browser worked fine after that. The internet2.voicestream.com APN works for me. epc.tmobile.com doesn't. I'm on Even More Plus plan with unlimited everything + unlimited smartphone web plan addon.

Maybe reflashing your device will help?