I picked one of these up at IPP. I've got to say, I'm not overly impressed. It's a great puzzle, but the knobs are too small. Even for my little fingers-I'm not sure how some of the 'less than delicate' gents would e able to work it.
I received mine today. I have average size hands and have no problems with the knobs. They don't seem overly small to me. I had no problem scrambling and solving it. It can be a little tricky keeping both half lined up when you position it to move all 4 sections at once (one section rotated 90 degrees from the other). Even though there are detents to hold the halves in position they are light and it is easy to have the halves slip out of them.