Rick Cockrum writes about wysiwyg editors for Habari, noting that Habari's editor uses raw HTML by default. That might be fine for techie geeks, but is unlikely to go far in the long run.
The first option you have is to use an alternative HTML-izible markup, and there are plugins available for Textile and Markdown (actually two for Markdown, here and here, though I really wish they could merge into one version). That may still be too geeky for most.
The second alternative is to use one of the recently released WYSIWYG plugins, of which there are three. First, the TinyMCE plugin, which I've released myself, though at some point I'll probably donate it to the community. Second, the NicEdit plugin, started by Christian Mohn. Third, jwysiwig. Both NicEdit and jwysiwig are now in the Habari community repository and owned by the Habari community. However, I've done significant coding on all three of these, so if you have any comments or feature requests, please let me know.
So, back to Rick's post. He accurately points out some shortcomings of each of the editors, and in a comment I added some more, which I'll briefly recap. None of the plugins are very configurable. Only TinyMCE is resizable. jwysiwig doesn't work with the media silos (a huge sin, because I think the media silos are a killer feature). Once Habari 0.4 has been released (soon, soon, I hope) I'll try to fix all of these issues.
Additionally, TinyMCE is not tiny, but there isn't much I can do about that.
Actually, the biggest driver for me doing any work on them at all would be for people to let me know that they're using them.