I have this problem with my iPhone 6, my navigation apps stopped working when I upgraded 9.01 and the issues have not been resolved for me with 9.02 or 9.1 upgrades. My navigation apps have worked maybe 3 times total over the last couple of months, I attempt to use them still on a daily basis even though they have been incredibly inconsistent.
I had absolutely no issues with my iPhone and using the navigation before upgraded it in September, the navigation has worked fine for almost a year, nothing else that I know of has changed except for the fact that I upgraded my phone. I have tried resetting, turning off and on, taking off the case, and everything I can think of/ find online.. Nothing has helped.
I have never considered switching to a different brand until now, this navigation/location issue is causing major issues for me.