Absolutely its worth it! It will keep you from storing media on your device and wasting memory. I have 400+ songs, many videos, several pics stored, and ringtones on mine.
Posted from my CrackBerry at wapforums.crackberry.com
Yes, verizon threw in a free 1 gig when I purchased my phone but I went back and got an 8gig (anticipating the OS upgrade) with corp discount. I listen to the music at the gym.
I have pictures, music, ringtones on mine. Also handy as a flash drive in a pinch. Needed to transfer files from home to office. Now they're on my berry and once I get to work they'll be on my work pc.