Today i tried the first time to do GeoCaching with my Nokia N810 running the Maemo (which is a Debian-based Distribution). I already own a Garmin Geko 201 with which i found 100+ Caches, so this is my reference.
The GPS-Receiver of the N810 is better than the one in the Geko (at least since i use the fixed gpsd, which normally shouldn't do something on the performance, but in my case... it made me feel better), so fixes come faster, and more accurate than on the Geko. (from hearsay the SirfIII-Chip is even better)
I wrote some programs to be the glue between Geocaching-Websites and GPSdrive (which depends on MySQL) and i modifed those to put the information into SQLite, which is the Database used by Maemo Mapper.
If i pump all my waypoints in such a file (which are currently 94607) Maemo Mapper gets slow. so slow that Maemo Mapper becomes useless.
On the Garmin-GPS-Receiver, i can have only 500 Waypoints, but i have a 'goto'-function, so i store my destination coordinates and say 'Goto' and the thing provides me an arrow which points to my destination and shows the distance (it doesn't know about ways so it points the direction directly, but that is usually fine as GeoCachers often are so abroad that no one has maps about the area.)
In Maemo Mapper i couldn't find such a function. I can say 'Goto Coordinates' and then it centers the map to there, but there isn't a sign and no line or arrow which direction i have to turn to. This is a problem (or something for the wishlist.)
So from GeoCachers view (and those people who want to navigate for other reasons) free Navigation-Software for Linux is an area where more work is needed.