I'd say the big standout would be the section on having only a few fonts to choose from, odd both in the current context generally where there's now a paralyzingly large number of fonts to choose from as a web designer, and also in the specific context of being presented on a site that's clearly using webfonts.
The Internet Archive's closest look at the original [1] isn't quite from the day of but it's probably the same styling: a classic "Helvetica, Arial, Verdana, sans-serif" font stack.
The grandparent comment called out the usage of still-appealing examples, but the original itself viewed in its original style is a good example as well, and really a better illustration of the post's point. Despite using a single "default" font, simple things like the choices of text width, line height, and differences in size, weight, and spacing of the headings have kept it attractive and readable.
Interesting to see the original. To me, that one feels like a much clearer presentation of good typography. For example, in the "modern" version the first thing that crossed my mind is that ironically the quote at the start of the article isn't clearly presented as such. In the original it much clearer is presented as such.
Ah yes, quite a lot has happened in webfont space since then. Their original layout is a great argument for having a sense of grid systems and page layout, especially being long-before sophisticated grid css would come to browsers.
In case you, like me, miss the dateline at the top and become more and more puzzled by the arguments and examples presented.
I will credit the article for using examples that are still visually appealing today, even (especially?) the 2004 blog.