NOT SUPPORTED IN ALL AREAS!
Just a warning to those who might be inclined to purchase the HTC One Developer's Edition directly from HTC. I bought it and it would not work at higher speeds on T-Mobile's network in Salt Lake City, Utah. It would only connect at 2G speed ("E" data icon). I contacted T-Mobile Support and got to second tier support and they confirmed that 4G speed will not work in my area with the phone purchased directly from HTC. It may work in other areas but you will want to confirm that with T-Mobile in your area before you purchase it. Otherwise, you have to wait to get the 64GB model if/when T-Mobile gets it. Or settle for T-Mobile 32GB model.