And everything could have been avoided by Apple choosing to wait a few months (or, more realistically, by working with Google starting much earlier) to make sure a Google Maps app was on the market when iOS 6 was released.
Your implication is that Google was surprised by what happened and so wasn't prepared with their own app. This strikes me as implausible. Apple's purchases of mapping companies was well publicized, as was it's slow break-up with Google. So if we're allocating blame for Google not being ready, I'm going to go ahead and lay that at Google's feet.
If we're talking about blame for Apple Maps being sub-par, obviously that's Apple's fault.
We do know that Google started pushing ads into Maps API results in such a way that had nothing to do with any negotiations with Apple, unless they fucked everyone by intentionally cutting quality data to Apple users.
Google makes money off of us primarily by selling our data, in one way or another. Apple makes money off of us by selling us phones, primarily.
One of those companies (Apple) was dedicated to keeping the customer experience positive and found themselves with few options. The other (Google) took an action that harmed customers they shared with Apple, to hurt Apple.
I know who I want to keep doing business with, as Google begins to close the Android ecosystem and people tend to forget that a significant core portion of iOS is open-source, just like OSX. I doubt Android will continue to be much more open.
If we're talking about blame for Apple Maps being sub-par, obviously that's Apple's fault.