From the creator:
The design is skeuomorphic, inspired by old radios. Kelly Ballweber, our Dieter Ram-obsessed designer, put a lot of effort into the details (shadows, glass reflection, metal texture, colour hues, audio hole size, etc); he wanted users to have a ‘Startrek Tricoder’ experience, where the iPhone feels like a dedicated portable device for the function at hand.
Mission:Park! is an incredibly beautiful app. Usually, I don’t find skeuomorphs appealing, but when this much attention and care is taken in making an app as realistic as possible, it’s hard not to. The nostalgic feeling of using old invention is most certainly conjured by the user interface and, as the realist approach to design doesn’t stop at the look of the app on the surface but goes deeper into the feel of it, it works very well in creating an exquisite example of interface design.