Nike Running app has finally got a redesign, but not a complete one yet. When you update the app, there is no actual functionality that you can see but the design is new.
It did not adopt the flat design of the iOS 7 to reflect in their app but they did that when iOS 8 released. You see it right from the icon of Nike Running app when you update it, flat and minimalistic design. You no longer have animation oozing around in transitions. Just flat and good. Apart from this, all the basic elements have more or less remained the same.
One thing the Nike Running app does offer is data to the Apple Health app. It offers NikeFuel and miles as data to the Health app.