I've recently bought a 3590 and am very disappointed at how one can't load waypoints from Basecamp or MapSource along with their associated symbols into the 3590. Loading waypoints via the POI loader doesn't solve the problem either. The waypoints load ok but the various symbols I've used are all replaced by a square with a heart in the centre.
I've had a couple of calls with the Garmin support centre and so far all I have is acknowledgement that there is a problem.
I've seen complaints of this shortcoming on another forum and so far no one seems to have found a way around it.
Whats the use of having great trip planning programs like Basecamp and MapSource if Garmin's GPS devices don't support their capability (unlike previous models). It almost seems as if the design team doesn't understand how many people uses their software and devices.