First off, I really like the look of the IOS6 Maps app and the turn-by-turn navigation design is excellent and extremely responsive. Love the autofill and history functionality as well.
Transit info is not relevant to me so I never missed that and am sure that the 3-party approach will yield superior tools/results to anything Google within months.
That said, my gripe has been with the route guidance. I have tried using it several times going to addresses that I know the fastest routes to and within one exception, all routes were either slower or false. Rather than using highways, it routed me through city streets instead of highways just to end up at an incorrect destination.
And it wasn't a case of wrong entry either; I needed to go to a car dealership, entered the name and routed myself to the location from the pin info. I ended up at a golf course 3 miles away via slow streets while the car dealer was right on the highway. The map even showed me being miles away from the pin, but when restarting the route, I was told that I am 100 yards away...
The data was so wrong that I feel that there must be an obvious bug that should be easy to correct, but at this point I can't use the app for routing in my area.
Am eager to see an update taking care of the issue as the app is miles beyond what Google had on IOS. For all the complainers that hype the issue should remember that an app is easy to fix, but a shitty (*insert the brand of choice in here) phone will annoy you as long as you own it.