It looks like the CSS is selecting some variant of Palatino. A classic of the genre, it's a very well-respected typeface for books, articles and other long-form written works. However, like many typefaces designed for print work, it doesn't take kindly to on-screen display. Exactly how readable it is depends on which version of Palatino you have, your OS and font-rendering configuration.

If you're using Firefox, I heartily recommend going Preferences -> Content -> Fonts & Colours -> Advanced, choosing a nice readable set of typefaces (such as the Droid family, if you have them, or Lucida Grande on a Mac), and unticking "Allow pages to choose their own fonts".

It looks fine to me. What browser/OS combination are you using?