As a reflection of my previous description of a smarter way to download maps, I would also suggest that the display of the route would benefit from a slightly more automatic mode. The level of detail to display could well be chosen automatically based on a few parameters, such as current travel speed, distance from the next way-point, shape of the route ahead, and availability of detail maps. I realize the current design has preferred battery lifetime and has been limited by the hardware capabilities; however, these suggestions should not be greatly more demanding of the hardware.

A few such suggestions also come to mind; besides the semi-3D tilted map display I have read the author is considering, a "smooth zoom" function by map scaling would make the detail level selection a less jarring switch, especially when it was automatically chosen. In addition, at least this writer is challenged by having to read routes where the direction of travel is, for example, down-and-leftwards. Visualizing correct turn directions becomes an effort not always easy to afford while having to make quick decisions in traffic. The map doesn't need to be rotated in real time with 360 degrees of freedom to assist the user in these circumstances; simply turning it in 90 degree angles might be sufficient.

That is for how the display works; as far as how the program reacts to user input, a few small changes here and there might make also that better when considering that this is a program used while mobile and outside.

Tapping on the map currently centers the map on the point tapped, or if the tap is on a POI (or very close to it), brings up a small message box with the POI name in it. I would suggest to make tapping always perform the same actions; zoom in on the point tapped, and display POI or way-point data if available. Re-centering should be done instead by tap-dragging a point on the map; a function which currently behaves as if the screen had been tapped in the position where the drag ended and pen/finger was lifted, exactly the reverse of what such a gesture would be expected to mean (try it to understand what I mean).

Zooming out can also be supported; either by tapping on the center of the map (where instead of meaning "center and zoom in" it will mean "show more around this point") or if the tap-drag action covers a sufficiently large area of the display, zoom out to display both previously visible as well as the revealed area. This behavior has precedent in other applications, is quite predictable and easy to get used to (especially if the UI's feedback to the action is made richer by scaling up/down smoothly instead of a sudden 2x scale change. It should also be nicely forward compatible to a new mode if and when future tablets support multi-touch displays.