Why do this PDF's fonts appear unreadable on my machine?

I'm trying to read The Art of Assembly Language as per this answer on Stack Overflow. When I open it on my Ubuntu 12.04 box, it looks like this:

I haven't tested it on another machine, but this can't be intentional. What is going on, and how can I fix it?

Edit: The above screenshot is from Chrome. It look like this in Evince:

Still squished and hardly readable, but better. Is there anything I can do to fix it?

The document specifies a bunch of fonts (for instance, Garamond which is the main font used in the document) but doesn't have them embedded. So your system renders it with what it considers the closest font it has. I'd consider this a malformed PDF; if you're using a font that's not widely available and don't embed it, users will have a hard time reading it.

You can install Garamond from here: http://www.fontage.com/pages/garamond.html

Download the garamond.zip file, uncompress it, and open each of the .ttf files that appear. They will open in Font Viewer. Click the "install" button to install them to your system. They will be installed for your user only, under .fonts. Once they're installed, open the document with evince which should pick up the new fonts and show the document as it was meant to be seen.

To know which fonts a document uses, open it in evince, go to File -> Properties, then to the Fonts tab. Any fonts that say "Not Embedded" are, well, not embedded, and in order for the document to render 100% accurately you'd need to have all these fonts installed on your system.