Mapper since: July 14, 2010
Lots of pretty maps based on OSM exist (even if the rendering at www.openstreetmap.org is pretty ugly). But routing, at least in my part of the world can certainly be improved.
It seems there are two major issues:
Address information is very sparse. If you are online and the routing engine is setup to use other sources of data it can be worked around. But for off line work, like OsmAnd where you are out of cellular coverage, this can be a deal breaker.
Speed limit information is spotty. So even if you can locate the destination the best route may not be found and even if found the travel time estimates can be way off.
So that is my personal area of focus: Collect speed limit and address information for OSM. So far it has made OsmAnd, OSRM and other routers much better for me in my local area. Perhaps it will help others too.