Usability of precompiled Garmin image files (gmapsupp.img)

There has been a long message thread on the Garmin newsgroup on UseNet about using precompiled OSM maps as drop-in replacements for the expensive commercial Garmin updates. I was intrigued by this, and so I downloaded the Dec 2 OSM for the United States for use in my Nuvi 205W (http://daveh.dev.openstreetmap.org/garmin/Lambertus/latest/). I selected the OSM map under the settings menu and disabled the built-in CN NA 2009 data as per instructions on the OSM web site.

The gmapsupp.img file is twice as large as the Garmin files for the same coverage area.

The map displays funny - road labels do not use the customary US symbols (such as the shield for interstate highways) but just a rather generic rectangular symbol with the number within.

POI's do not dislay an address when searching; rather just the distance away and the county they're in. Already saved favorites display with full attributes, but a new POI will be saved without an address or state.

It is impossible to enter an address to route to, because there is no way to enter the state (I'm in NJ). With the Garmin maps, the last searched-for state is displayed at the top of the menu and you have a button with which to change to another state. With the OSM map, you can only enter a city name, or "Search all". I entered an address in Morristown NJ and it was not found by either method.

I've gone back to the Garmin map for now, as the OSM does not work well with the Garmin operating firmware. Have I downloaded a map from the wrong source, or is there something else I'm missing here? Thanks!