Voice prompts seem to be spot on and easy to hear on my 6800.
I've been using it on every trip in the car since I DL'd it, and it's pretty accurate.
Some issues...
Unlike Live, I can't use it to find contacts. So, if you have a new customer, add them to your contacts, you're going to have to switch between contacts & amAze in order to enter the addy.
It tried to send me the suicide way down a one way street, but quickly recovered when I refused.
The satellite imagery & topo maps don't work... and I'm in a large suburb of Atlanta... a city of 5 million.
My arrow is now an X-Wing fighter with my name under it.
If Live ever comes out with voice prompts, this and Google Maps are toast, though.