Well, the HTML editing of Zim might be its weak point. The formatting is a bit finicky and if you change the styling too many times it sometimes gets in a situation where I cut-copy in a text editor and paste it back to restart with no styling.
Aside from that, it has lots of plugins and can easily be exported to a full website. In fact, Zim's website is made with Zim http://zim-wiki.org/.
Bu the killer feature is that it's a wiki: you can link pages together and easily re-organize them. It's fully searchable and you can embed rich content. Also, all the pages are stored as ReST documents (I would have preferred Markdown), which makes them editable with a text editor. Also, Zim can use Git or Hg for version control.