I've heard it is good, though I don't think it was available at the time I was using the Mozart. What I did have was "Orange maps":

https://mspoweruser.com/orange-maps-for-windows-phone-7-come...

This was OK when it worked, but it had a habit of freezing the phone and requiring a reboot. Also, it would refuse to start if there was no mobile signal, so I would frequently have to drive a few miles from my destination (I always seemed to end up somewhere with no signal) before I could start navigating home.