Don't listen to the people who tell you you should get a card reader instead of the cable.
If I had to choose between cable and reader, I would go for the cable.
As was already said, using the cable you can transfer stuff with GPDrive pretty quick, I don't think it's slower than a card reader. At least not than MY card reader.
Also, some programs (fday-emus, GPMadMP3) have file-transfer-capabilities, too, that need the cable.
You can carry the cable anywhere easily.
And finally, you can use your GP32 like a USB mouse or USB joystick with the cable, it works great!
That being said, get a card reader, too, because it's more convenient if you want to transfer many files and don't want to bother about draining your batteries.