Well...the only reason I tried this out is for public transit directions. It doesn't personally affect me (I have an Android phone) but I know a few people who felt hoodwinked when they upgraded to iOS6 because Apple Maps has absolutely zero public-transit features, something they rely on every single day in the city.
So I did a test...how to get to the De Young Museum from my friend's apartment.
Google Maps (Android version): Gave me an "interesting" route, but it's probably the one I would actually take. First it tells me to walk nine blocks, then get on the '5' that goes to the park. The nice thing about Google though, is that it lets me choose from three alternate routes besides the main one. So if I don't want to walk that far, it gives me a choice of an alternate route including a closer initial bus.
Nokia HERE: Gave me a very conservative route. I guess Nokia doesn't like walking, because they had me walk just one block to take the '47' down to the same place to catch the '5' that Google had mentioned (interestingly enough, this was NOT one of the four routes that Google had picked!). The bad news is that you can't select any other routes.
Apple Maps: Supreme fail: it didn't give me anything. There is actually a button in the app for public transit, but all it does is take you to a listing for other apps!! Wow.
So, Nokia HERE is technically better than nothing, but I think most iOS6 users are going to look right past this to the new iOS Google Maps coming over the horizon.
HERE is also quite ugly (low res everything on my iPad, bland colors), and the zooming is terrible--you can't zoom and move the view, which might not sound like much, but after Google and Apple maps you really expect it.