I'm giving this 5 stars because I really enjoyed this story. It's silly Golden Age Sci-Fi Pulp but it's well written silliness. It even had some nice pathos in it when Ling, the hudge grunt of a man decides to stick with Fitzhugh Parr (dumb name btw) as they head off Into exhile together.
I am calling BS on "The Evolution" machine though. Using Vibrations of some sort, it can De-Evolve a man. And when you flip a switch, you can reverse the process and Re-Evolve the same person back to homo sapien status. I mean.....seriously? Lol.
I listened to an hour audio version of the story as I went out shopping, and it had me smiling all the way.
I started chuckling when, near the end, when MWW put his tongue firmly into his cheeks and started playing with the Sci-Fi Pulp conventions of "The Helpless Girl" protagonist and the swave, clean cut "Action Hero" (with a nicely clipped mustache) protagonist.
Lots of fun and an enjoyable experience.