Yup. A friend gave me his "old" iPhone 4s a few months ago. I don't have a data plan, just a flip phone for emergencies. But I use the iPhone and apps almost daily, as a mini-tablet through wifi, for snapping photos, etc. The GPS still works to record location data on my photos and videos. And I can access some map features without a cell phone signal.

I tried Strava, Map My Ride and other cycling apps, but quickly lost interest. I just ride for fun and don't really care about that sort of info. However my map access is very slow away from home and I might get a prepaid data non-plan just for better access to maps while I'm out exploring.