I'm torn, this episode is a nice breakaway from the formulaic criminal pursuit on Hawaii Five O, but the reason it has appeal to the regular viewer is just contrast and emotional stimulation, not quality.
So as an actual episode, it's 0 out of 10 for reasons listed below, but for wacky breaking through the wall of tradition, I'll give it 5 of 10.
It leaves any story behind, just to let Hume Cronyn have an episode to perform. So that's actually a good thing most of the time, but Hume blasts through the characters, makeup, and costumes here like its a vaudeville show. An his acting is painfully over the top and obvious. It's pretty much a comic book episode, which of course is why it's appealing from an energy standpoint, but that doesn't make it great.
And speaking of vaudeville show, the Morton Stevens score is not a thing of brilliance, he simply wrote up or found a few minutes of 20s ragtime, and he loops it through the wacky parts. Again, it's a contrast to the usual corporate stock music, so it rises in interest due to novelty not quality.
Lastly, although the story is not really important to the episode, it unfortunately totally discards any sense of reality, as the criminal bases his enterprise in a location that includes a massive amount of physical evidence to be caught with, rather than using a generic location - say an ordinary home. This simplifies McGarrett's job to a quick trip to the forensics lab and a casual drive. (Trying to avoid spoilers here) In summary, this episode is the typical "comedy escape" episode that producer/writers throw in when they or the cast are tired of doing the same thing over and over, or the ratings are slipping.
Not sophisticated, not complex, not deep, not unique, not that interesting. I came here to seek out any mention of Cronyn's overacting and found only goofy praise. Oh well.