Many of your points are true. Maemo Mapper does use raster maps, but you have the flexibility of building your map database as large or as small as you like (with tradeoffs between disk space and detail). And route generation does require internet connectivity, although Maemo Mapper does include auto-rerouting functionality (again, requiring internet connectivity).

But Maemo Mapper offers a few advantages over Google Maps in the browser: performance is better; screen real estate is more efficiently used; GPS devices are supported; and you don't have to be connected to the internet in order to view maps (only to download new ones).

All of those advantages are also present in the built-in map application ("Maps"), although routing costs money. The functional difference is that Maps uses vector data, while Maemo Mapper uses raster data. The other difference is that Maemo Mapper is free and open source.

Good street data is costly in general, which is why there are so few free routing alternatives. RoadMap uses U.S. Census information, so it is limited to the U.S. and lacks certain important information (like speed limits and road directions). OpenStreetMap is making good headway, however, and someday it may be complete enough to provide ubiquitous routing. Navteq and its ilk are the only complete solutions at the moment, and they are costly, which is why Maps's routing is not free.