My friend just bought a portable one at a quilt show as neither of us have wall space. It folds up like a camping chair, but opens to accommodate a king size quilt, stands at an angle and it VERY sturdy. I'm going to the Sewing Expo next month and asked her if she liked it- she loves it! She has the foam core one made and it works fine, but just no room in her home in Florida.
For the Newbies- they're like an artists palette- you have to stand a few feet away from the blocks to get a true idea of what the colors do- the flat bed just doesn't work the same!