Thanks again for publishing this.
How much of the book is useful (probably wrong word choice) if the reader does not know Rails?
My guess is that an accomplished developer with a few languages under his/her belt might be able to understand and translate aspects of the code. At one point it becomes more opaque and you can't go further without learning Rails. I know nothing about Rails, which means I don't have a real sense of how difficult it might be for someone coming from, say, Python, to read and understand Rails.
Note: This isn't criticism. I am interested in the book but don't work with Rails and don't have the time to dive into learning it. Because of that I am trying to determine if the book would really be useful to me. I am currently working with Python and have good command of probably a dozen or more other languages.
Additional data points are always very much appreciated and it's very good of the author to release his tools and methods for others to learn from. Of course, the $5k in 2 weeks doesn't account for the time it took him to write the book or the opportunity cost of not taking other work, so this still might not have been a financially worthwhile venture, but hopefully it will keep selling and he'll publish more about it.