Well, if you're looking for a brief introduction to ML that book could be of some use for you. Unfortunately, it doesn't go far beyond that.
Code examples that are bundled with the book have-not been updated for a long time, therefore some of them don't work.
I reckon that If you had read a few blog posts from 2017 titled "Introduction to Machine Learning" with no Ruby code examples you would have known more than what this book teaches you.
My score is 3/5