perspective from abroad (Japan):
apple maps still not very usable in japan as so little detail in the maps themselves is provided.
it has improved, but still not near enough.
however, this year apple has really improved its integration of and extension of map based info/features within iOS. this means that for the first time i have put apple maps on the front page of my iPhone home screen. its clear that total iOS integration of map based and map related info will make apple maps useful within the iOS system.
apple has really increased the amount of hooks into map related data.
transportation (train, bus), giving others yr location and expected arrival times, etc etc. all this has improved.
but just in terms of map detail itself, in japan #1 maps with detail useable in iOS is definitely yahoo. (yes, yahoo is a very very big thing in japan. really detailed map data, pinpoint weather location, public transportation etc).
#2 is google.
#3 is apple.