I'm going to sum up my iOS 6 review very quickly: It's great. Except the new Maps, which are pretty good, not as good as Google's, but will improve fast and are necessary to hold off Android.
Why, do you ask? Simple. When iOS first came to pass in 2007, Google was a key partner. They provided the default search engine, the mapping data, and a YouTube app right on the home screen. Wow stuff. They were a key Apple partner, and then-CEO Eric Schmidt sat on Apple's board.
Then things changed. Google decided that they needed their own mobile platform, and begat Android - which due to Google's licensing terms (free) has become the most popular mobile operating system out there. It's not the highest-value for a lot of reasons (mainly because a lot of the installed base consists of budget users and cheap phones, where basic smartphones replaced the old-school featurephones), but they have a huge presence, and Android users get one big advantage over iOS users (who have to access Google Maps via the API instead of directly): Google Maps natively supports turn-by-turn directions, but not through the API.
And as smartphones become the standard navigation device, relying on Google became a key competitive disadvantage for Apple - as long as Google is their map vendor Apple can't offer turn-by-turn.
So this had to change. Rather than partner with Microsoft/Bing or one of the other map companies, Apple opted to do it themselves (with the help of mapping tech companies they bought), and Apple Maps will soon be on approximate par with Google after a couple of months' worth of correction and crowdsourcing.
Until then (remember, iOS 6 is less than a week old in public release), it'll be a little bumpy. But also remember Google took years to get good at mapping. And they still have errors sometimes. Apple's gotten much of the way there in one release. They'll get better fast.