Although I hesitated at first, I was interested to see for myself the Kuku's puzzle mechanism. So I finally bought one after Sonic Games offered a special website price discount. Thankfully my copy did not appear to have quality issues and overall fit and finish is of a very high standard.
The object of the puzzle is to unlock the three pieces and remove a small plastic token with an imprinted number. Kuku owners, once they solve the puzzle, can register this number on the related Kuku website, play a game and stand to win a prize. According to both Neil and Jonas Bengtsson in his blog, there are apparently two versions, medium and hard; but I do not know which my copy is, the medium or the hard.
When I first examined the puzzle, I had a pretty good idea how the three interlocking pieces were held together. A number of other metal puzzles in the same genre, several of which have been reviewed on this blog, apply a similar principle to that of the Kuku. Gravity plays an important part. The difficulty of the Kuku perhaps stems from the fact that all three interlocking pieces forming the sphere are symmetrical, so trying to determine the orientation of the puzzle vis-a-vis how gravity applies makes it very challenging indeed. Like the Purple Isis I wrote about earlier in this blog, I had no intention of spending a lot of time on the Kuku. Checking out the internet and help videos on YouTube, I was able to take apart the Kuku quite quickly. I will not go into any "spoiler" details here since there may be readers here who are determined to solve the Kuku on their own. But looking at the internal mechanism, this one is not easy to solve repeatedly.
For the design and engineering that goes into the manufacture of a Kuku and from both the puzzle aspect and price point (and just so long as there are no quality issues), I would say the Kuku is certainly worth acquiring.