The greatest disappointment (for me) comes from the fact that free turn-by-turn navigation is not available for iPhone 4. That particular feature made me happy about Apple's switch from Google's to their own solution. I couldn't care less for Siri, flyover maps or panorama (seriously, that one is iPhone 4S+ too), but navigation? That's a deal breaker. If Google won't provide this with their app I won't stick to iOS when my contract ends.