Is the LensPen Panamatic of any real use for creating panoramic shots or is it a waste of money?
I've never used one, but as far as I can tell it's just a bubble level combined with a device to click through increments of 15 degrees or so.
If my job was shooting panoramas all day long then it might make the process a little less laborious, but if you're taking time of the composition, lighting and camera settings for your panorama then lining the shots up shouldn't take too much effort.
I normally line up landmarks against the focus points to ensure a consistent overlap. Spirit levels can be useful, but if you don't have one shoot the first and last image of the panorama as a test to check your tripod is level.
Depends on what type of panos you're shooting. The Panamatic doesn't rotate the lens around the no-parallax point which means it's probably not good for panos in smaller spaces (i.e., indoors) where parallax may cause stitching errors. And it does not allow for rotation in pitch, like a two-arm pano head will, so it's probably not good for 360x180 panoramas that need to cover the zenith (straight up) and nadir (straight down), or for shooting multiple rows of images, so may not be best suited for gigapixel high-resolution panos.
As someone who often shoots 360x180 panos indoors, I wouldn't get one (I use a Nodal Ninja II). But everybody's needs are different. And it looks to be low cost and useful for leveling the camera and tracking coverage for slightly longer lenses if you are shooting landscape panoramas. I would, however, suggest learning to shoot panoramas handheld first, and see if you think you need this tool, or whether a plumbline and a hotshoe spirit level might work better for you instead.