Apple posted job adverts for six iOS map engineers within the past ten days, perhaps preempting the storm of criticism over the controversial new map app in iOS 6.

Any effort to boost the software’s team could be seen as too little, too late after fanbois and fangrrls across the world branded the new satnav-like service as rubbish. Apple had decided to replace Google’s map app with its own program in the latest version of its mobile operating system, which was unleashed on the public this week.
— The Register (linked)

Apple doesn't "scramble". They dont have knee jerk reactions. The jobs postings The Register refers to were posted a) on the 11th of September which was the day before iPhone 5 event and b) the day before the iOS 6 GM was produced — no doubt burnt into iPhone 5's in production from then on.

The maps aren't a one-for-one replacement of Google Maps, they never were going to be. They do offer some great new features that Google Maps didn't have available. The only thing Apple would never match Google on was the mapping data. But its important to remember that they can't get any worse than this. Apple's maps are only going to get better. Google better keep an eye on it.

Just another thing about The Register's article; earlier this week we had this from John:

Seems pretty clear the new Maps is going to be the biggest problem with iOS 6. Here’s the thing, though: we don’t know how much of this decision to switch was Apple’s alone. We do know that Apple’s existing contract with Google for Maps expired this year. It’s possible Apple tried to renew for another year or two and Google either refused (unlikely, I’d say) or offered to do so under terms Apple found unacceptable (possible, I’d say).
— John Gruber

To my knowledge there is no definitive answer as to whom decided that Google Maps was to be removed as the main maps source. Speculation points to Apple but again, not confirmed. Both companies have something to gain with this move, I would say Google is in a better position now.

My personal opinion after having to use the maps: It sucks. I had to load up Google Maps in Safari to access public transit information. I loved using Maps on my iPhone to route public transit trips because it was accurate and always worked. Many kudos goes to Adelaide Metro for making that work. I hope there's a way for them to continue to make it work in whatever application allows it to work.