I will be brief:
- It is really expensive.
- It is beautifully made. I mean it, it’s gorgeous. It is made from stainless steel, brass, and has some details (e.g., a dot of red paint) that make it look fantastic. It is precision made with high tolerances that give it a very pleasing, smooth feel.
- The locking mechanism is ingenious and unusual. I know of no other puzzle that uses the same principle.
- Like the best puzzles, it is easy and quick to solve if you know the trick.
That’s about it. Here’s a picture of it:
(I’ve included the Rubik’s Cube for scale.)
Other folks have reviewed it too:
- http://seekingariadnesthread.com/2014/01/12/the-eighth-trick-lock-of-rainer-popp/ (spoiler alert!)
So as you can see, everyone who plays with this puzzle is pretty impressed with it.