There are some places it's fine. Other places it's problematical. Other places it's a complete disaster.
The last two categories seem to outweigh the first for me. In the UK especially where basic things like searching for local train stations (we actually use public transport quite a bit here ;-) seem to fail completely in large chunks of the country.
Since my experience of Google Maps on the iPhone until the switch over was that - as long as I could get GPS and an internet connection - 100% fine the Apple maps app is a complete fail for me. I can understand that there might be reasons for it being necessary from the business perspective - but for me personally it now means I have had to have three map apps on my home screen to get around rather than just one.
I'm hoping I can switch back to Google Maps to have one thing that works.
I could rely on it totally.
I'm not going to say I can't see what the fuss has been about as I've seen enough examples to know that there are real and significant problems, but I can say where I live (west of Scotland) for my use cases (basic searching and navigation) I've not had anything to complain about.
Q: "Where's Dulles Airport?"
A: I couldn't find any places matching 'Dulles International Airport'.
Honestly, if anyone has a voice search that will find it, let me know.