I use PocketEarth when travelling with my motorbike and heavily relied on it on my last trip through South America. One major factor when planning a route is road surface (asphalt/gravel/dust). You need this information to choose the route and to plan ahead where to stop for the night.
The feature I miss most is the option to show the road surface type on the map.
Even if OpenStreetMap is far from complete wrt surface type mapping, with this feature it is easy to review the current state and update it during/after travelling. Currently PocketEarth is already the best option for overseas adventure travelers. With this option it would be plain awesome!