I have the 16gig version, but I wish that I would have gotten the 32gig.
The first thing you notice is that two full gigs are taken by the preinstalled items and the OS, which takes you to 14.
Personally, I have no interest in putting music on the ipad because I store all of my portable music on my phone and I rarely listen to music through my computer/ipad. I don't like to keep a lot of videos either, as I typically watch what I want to see and then delete it from the ipad. For that reason, I went with the 16gig.
With that said, I had no idea that so many apps would be so massive in size. I love apps with beautiful images and information, and I already have 3-4 apps that are over 300mb in size, along with a number of other ones.
Garageband is around 400mb
MOMA app is around 300mb
The Elements app/book is 1.3 GIGS!
I've had the ipad2 for less than a week and currently have only 8 gigs left with no music or movies. If I decided to go on vacation and put 3 movies on the ipad, I wouldn't have any space to rent a movie from the itunes store because of the space required.