PS Vita Reviews got in on the Deka Vita 7 Pre-Order cycle and has played around with this piece of hardware. Here are their final thoughts:
"The Deka Vita 7 is something interesting that no one could have seen coming from any developer. The downsides I noticed are that the screen looks a little on the grainy side, the speakers sometimes pick up some static noise, and the R2 and L2 triggers are a bit on the small side, requiring some adjustments. It’s not the perfect device, but it fixes a few of the Vita’s problems and is a welcome addition to the PS Vita family. It is also optimal for PSTV owners that want a handheld with a large screen and buttons that feel more like they came from a PS4 controller."