I just got one. It's an expensive upgrade but my old 660 was becoming unreliable so it was time.
So far I'm digging it. The hardware looks to be more susceptible to handling errors as the screen is flush with almost no bezel. A butter fingered drop might be fatal. I was quick to buy a standard case for it. Careful not to yank too hard on the rubber access panels or the hinged edge can get pulled out of place. As long as the rubbers are squished down good it should be nearly water-proof
Yes there is a steep learning curve as the user interface and the menus have all changed. Including some of the standard terms.
I found an article written up by the inimitable John Heath. It's 80 pages of detailed explanations of pretty much all of the how's and why's. Well worth the time to read through. -->
Article - Zumo XT - (Almost) Everything that you need to know | Articles | ST-Owners.com
After two weekends using it under pressure... Boot up is almost instant. The screen is bright and crisp. "Lane Assist" will now verbally tell you which lanes to be in. Overall the verbal directions are very good. The "Junction View" side screen info is much better. Capacitive screen with pinch, zoom, and rotate is awesome but still iffy with gloves on. Poking at the icons while moving is hit or miss. It recalculates way quicker than the old Zumo. Usually. I confused it last weekend by bypassing a waypoint (see John's essay about the difference between waypoints and shaping points). It just gave up and said "not able to calculate a route"! (You have one job!)
Telling it to forget the original route and plot a point to point course resulted in instant success. Sharing saved routes via bluetooth to another Zumo XT is amazingly easy. The new "points of interest" layout is confusing and I'm still getting the hang of it but it does work pretty well for finding food or gas along the way. You'll also want to check out the Garmin "Drive" app to supplement it with live data from your phone. You'll get side screen pop ups for local traffic and road construction issues. You'll also get email notification pop-ups. Nice if your phone is tucked away safe somewhere instead of mounted where you can see it. With the old setup all I would get is a ding or dong and not know exactly what just came in. Now I knew right away that my sister was trying to get in touch with me.
You can also pull up weather forecasts and radar and it will superimpose on your map display. Sweet!