Hopefully Google releases a Google Maps app into the App Store, like they did with YouTube. Apple Maps looks like a major regression from Google Maps.
Apple Maps is a regression in certain areas (public transit, as noted above), and advances others (the turn-by-turn experience), so it's a mixed bag.
At the end of the day, most of these things are reconciled through the app ecosystem: if you are heavily dependent on public transit, Google and other app providers support you well. If you're a driver, Apple and TomTom provide worthy solutions. And so on with walking and biking directions. We, as consumer, get choices and it's relatively easy to switch between them.
That said, even if they do submit one immediately, I'm afraid Apple will tie it up in review for a month or two to allow their version to gain a userbase. I know if a Google version were available upon upgrade to iOS 6, I'd download it immediately. Transit directions are a must-have feature for me.
I hope you're not talking about the "fly around" view when turning a corner, because that is the most useless feature I've ever heard of for turn-by-turn navigation. NO ONE should be looking at their phone while making a turn.
Maps has a huge local revenue opportunity for Google. It has user intent, most of the searches are commercial, you know the user's tastes and hangouts (through past searches), and the user is addressable (since they are close to the item of interest). This means high CPC rates (or equivalent) if you can deliver a real ad product. Thus, I'd bet pretty strongly that a maps product will be coming to iOS since Google would hate to risk losing those valuable eyeballs.