Remember the very first time you used the airbrush feature in Painter, Photoshop or SketchBook? It was a revelation, particularly if you'd ever messed around with a real airbrush; here you could get the same gradations without the hassle of dealing with the compressor, the endless masking and the non-erasable overspray.
The Kingspray Graffiti Simulator is even better, as it lets you virtually create spraypainted images on textured brick and the like without the hassle of getting arrested:
The attention paid to detail is brilliant. I love how you can see the spray leaving the can in bursts, and can get dripping if you hold the trigger down too long. I really hope that the actual app will also provide the sound of both the spraying and the marble hitting the inside of the can.
I don't mean this as a knock on anyone, but the images in the Kingspray gallery (created by beta testers) doesn't yet include any seriously Wild-Style-level burners. I'm eager to see how the gallery changes after the app is released, which should be on May 16th.