This title is incorrect and somewhat misleading. The link points to the homepage of an online book titled: "Small Memory Software - Patterns for systems with limited memory."
The PDF reader works fine for me - No crashes, Chrome 15 on Ubuntu 11.
I'd rather look at a nicely typeset and easily printable PDF (see an example from this book here: http://i.imgur.com/ZTq4s.png), and let the authors spend their time improving the paper, than an HTML version.
All else being equal I'll take more unicorn, please.
But the point is that PDFs aren't very compatible compared to HTML. Nor are they very versatile. You're limited to viewing them as intended (which may not fit your screen, eyes, or task very well) and searching is usually limited to a non-regexp find.