There is one problem with Waze. It will not avoid low overhead clearance areas.
I've got a 770 and my thought was I needed way more things before taking off on our trip than the GPS so I waited to buy it until the week before we left. Didn't bother to learn to use it (IT's a GPS how hard can it be???) Well, I couldn't get it to navigate where I wanted to go (Well, my wife couldn't) so I said turn it off and I used Waze. About 3/4 mile from entrance on the road that the campground is on is a low overhead train bridge. Yea, I saw the sign AFTER I turned onto the road. Made a long day just a bit longer.
I still use Waze side by side with the GPS and sometimes follow it before the Garmin but I will still use both for times when I'm in an area that's questionable or off the major highways.