One interesting thing I've noticed with the new Maps app in iOS 6 is that (unlike Google Maps) there's no longer an English translation for streets in Bangkok (or if there is I haven't found how to switch it on yet). I've tried searching for the common English spellings for some streets and it appears to work - but doesn't seem quite as accurate. And if you don't read Thai, when Maps isn't showing you the correct street, you won't be able to tell anyway. So, much as I like the look of Apple's efforts, I think what I really want is a native Google Maps app, with offline map storage...
Update: although it sounds like perhaps iOS Maps will be better for offline navigation anyway.