The smartphone seen above is the Desire 610. It was announced by HTC last week at MWC 2014, alongside the larger, more powerful Desire 816. HTC said that the Desire 610 would be available in Europe starting May, but it looks like it might also be launched in the US at some point.
According to @evleaks, the Desire 610 is headed to AT&T. Not long ago, we heard that AT&T would released the Desire 816, too. Even more, the second largest US mobile carrier is almost certainly also getting ready to sell the All New HTC One (M8) flagship.