The 3D Flyover mode is another new feature in iOS 6 and it is definitely impressive if you're looking at specific cities. The app has several areas modeled in full 3D, letting you swipe to fly over buildings or use a two-finger gesture to rotate, and it looks beautiful with smooth frame rates even on last-generation devices. But the feature is not without serious problems. When looking at some areas, visual bugs such as airport runways with bumps like a roller coaster and streets that startlingly drop off vertically are only a couple of many examples where the new feature falls short. I also wonder how much you'll actually use the feature beyond showing off to your friends.
The Apple Maps app is the company's first effort at creating a maps app, so I didn't expect it to be perfect, but I also didn't expect it to have this many problems. As much of the information is crowd-sourced (with user-driven information from Yelp), the app should get better over time. With all the bad press, there's no doubt Apple is working right now to update the app, but until it does, people who have updated to iOS 6 have few mapping options. While of Google making a standalone app for iOS, it's unclear whether you'll be able to get a Google Maps app on your iPhone in the near future. Unfortunately, as is, Apple Maps is not an improvement over the previous Google-powered app and you might be better off using a third-party maps app or Google's Web-based offering through your phone's browser.