Most professional photographers will tell you that an on-camera flash is fine in a pinch, but not at all conducive to excellent photos. The "true tone flash" on the iPhone is fine for what it is, but it won't do you any good if you're far away from your subject or anywhere but a very dark location.
The Nova is an off-camera, bluetooth controlled flash for the iPhone, and it finally gives us the lighting flexibility that us photographers have always wanted from the iPhone. It connects to your device via bluetooth, and is controllable via the free NovaCamera app. You can set flash power, color temperature, and even focus and exposure control for the camera itself.
Nova has a bluetooth range of about 20 feet and has a rechargeable battery that is charged with the included micro-USB cable. With 40 LEDs behind the built-in light diffuser, Nova can add natural looking light to just about any scene.