OnePlus X (unlocked) review:

The inexpensive OnePlus X is fast, beautifully designed and has some nifty customizable features but it is somewhat slippery, is only available by invitation and has limited compatibility with key LTE bands in the US.

The OnePlus X is one of the best budget phones of the year, but its limited LTE support make it a crap-shoot for US customers who want high-speed data.