It works extremely well, and is quick to set up. The image below (larger image if you follow the link) was taken with my Cybershot P100, and stitched with hugin:
I’ve highlighted the overlap between the images with a bright blue background, and only cropped the image for width. The Panamatic gives very even and level results.
There are a couple of downsides: you can’t correct for lens nodal point location (thus giving woozy effects if you used it for an animated cylindrical panorama), and the click stops are fixed at 30°, so you had better use a near standard lens. Apart from that, it seems pretty well made, and easily worth $40 for hassle-reduction alone.