Just finished a 3500miles roadtrip across the US with the VIA 1535TM.
Have to say, it's really good where it matters, in the actual guiding you, redrawing routes, finding satellites, voice commands, ...
From the moment you go in the menu's though, that's where it gets slow.
Sometimes you press something, and you have to wait a second or two for it to react and going to the next page.
Same with typing city names, streets, ...
It just feels sluggish.
Once you have the route set-up, nothing can throw the tomtom, no matter how many wrong turns you make. Even if you have a 3000mile route in there, recalculating is done in a fraction of a second.
If they can do something about the speed in the menus, then it would be a top device!