I have been testing Apple Maps, TomTom Sat Nav & Fog of World in iOS 9 since Beta 1 on an iPhone 6 Plus but the GPS has been very slow and even unresponsive at times, Making it awkward for navigation as it wasn't being updated accurately making your location jump about on screen or even stick in a location for several seconds before jumping to the correct location. Fog of world shows this off by leaving fog on areas you've just driven on but it doesn't remove it. Hope to see this fixed ASAP as it seems this problem to be all the way through from Beta 1 for me.