The best advantage of the application is the price, which is quite competitive. Maps are easy to load and view, although each high definition map takes almost 50M memory (simple paper scans), so the available memory should be considered.
I have rated the application as 3 stars instead of the 5 because of the following functionality must be a part of any topographical application (at least from my point of view):
1. Real time GPS tracking. To find the current position on the map a user has to touch a small "button" on the screen. How I suppose to track my real time movement on 4X4, ATV, bike, etc.? There should be a way to lock GPS tracking so it would refresh the current position automatically (I believe its not a hard thing to add though).
2. Dropping a pin with description (like camp, waypoint etc.). In case if you found a place which you would like to visit again - you should be able to store the location. Ability to add pictures to the stored locations could be a very nice feature too (after all, iPhone has a camera).
3. Storing tracks. That was a bit surprising a topo map application does not have this functionality.
4. I think the user interface could be neater too. The most annoying thing is the thick blue crosshair of the current GPS position - it is so huge that it even does not fit the screen when you zoom to the maximum level of details. Although the crosshair is partially transparent, I believe the application will look much better with some small and nice 3D pointer which would not grow or shrink when you zoom the map.
I hope the mentioned functionality would be included in one of the next versions, and then I would definitely give the app the highest rating.