I still have the Google Maps app on my phone, but haven't used it in probably two years or so. Completely happy with Apple Maps, at least in North America. It has a far better UI than Google IMO.
When traveling it's a good idea to check which maps app supports public transport at the destination. I also sometimes use the HERE app, because it can download maps for regions or countries in advance so you can use it offline in case you don't have data service while traveling.
Have been using Apple Maps exclusively for about a year, and considering that Tokyo is the worst when it’s comes to inconsistent addresses and finding places, it works just like a charm (travel time is a godsend, especially when you have several appointments in several locations through the day). I was really only missing street view a bit, so this will make me a happy camper. Also from the demo, Apple’s Look Around seems to be more seamless and way cooler.