Somebody hasn’t heard of HPMOR...
I clicked, and was very disappointed. What might a version of my Death Note essay for Harry Potter have looked like? I had no idea but dearly wanted to find out.
To explain my downvote: both the title and the description of this post are misleading, and the link itself is not particularly interesting. A better title and description might reduce the number of downvotes you get.
I wouldn’t be terribly surprised if David MacKay has heard of HPMOR, actually. Also, the textbook pitted against Harry Potter there is very good indeed.
(Also: although I can see why this post got downvoted, I really don’t think it deserves to be at −8.)
I have the paperback edition of MacKay’s book. A lot cheaper than thirty pounds.