Finished a one way 1250km road trip the other day. Was using WIMGPS with dialup networking over bluetooth (CDMA, 1x data access).
Overall, it worked pretty well.
One problem that kept recurring though:
After it was working fine, when the connection dropped, WIMGPS would freeze (not every time though.. maybe 40% of the time). Restarting it didn't work as it would just freeze after sending a GPS coordinate. The only solution was to reboot once or twice.
Other than that, there were no problems. I had a few people keeping track of us online and it seemed to work seemlessly (except the time zone stuff, which I think I may have messed up). The best part was when we were on a ferry boat and the gf did a screen cap of my location being in the middle of the water