I noticed this over the summer when I was in Beijing/Shanghai with the iOS 6 beta. As soon as I got on the Chinese cell network, the maps suddenly changed to the AutoNavi maps, which although they turned out to be significantly more useful, they weren't vector-based maps and you couldn't rotate them like Apple maps. I also noticed a few other things like I no longer had access maps of any other country and after comparing the maps to the Google Maps in China on my locked iOS 5 phone, the AutoNavi maps were SIGNIFICANTLY more useful (and even saved me when I was lost one time).