Setting up a Wysiwyg or rich text editor in Drupal is a straightforward task: you download the Wysiwyg module along with the library of your favorite editor and you're good to go. You will run into issues when you're using CCK multiple value fields though:

• You will experience data loss when adding more fields: all content added to existing fields will disappearing when you click the "Add another item" button to add a new field.
• Depending on which editor you use, there's a chance of hick-ups and data loss when using the drag-and-drop interface to rearrange fields.
• Depending on which editor you use, you will run into different kinds of unexpected behaviors when adding your first new item after clicking the "Add another item" button. These issues can range from the editor only appearing on the first field, to only appearing on the last field, or from the editor disappearing completely.

The first two issues can be fixed by installing the Wysiwyg API CCK Integration module, which itself depends on three other modules: JS Alter, jQuery Form Update and jQuery AOP. These modules require no configuration: just enable them to fix the problems.

The third issue however is more tedious. I've tried fixing the bug with hook_form_alter() and CCK fields along with the Wysiwyg integration guide but these don't play along nicely. The added difficulty is that the problem varies depending on which editor you use. The only bulletproof "solution" I've found this far is to simply use the FCKeditor editor: it's the only editor that doesn't appear to cause any unexpected behavior. Do note that these problems are only fixed if you use the FCKeditor with the Wysiwyg module: the FCKeditor module itself still has these issues.

I came across this interesting slide on Drupal Talk:

"Drupal 6 modules" by avorio

Last year I did a comparison between Drupal and WordpressMU in terms of how both relate in terms of the multi-user blogging experience. The conclusion was that WordpressMU had all the bells and whistles and that it was clearly more experiences in terms of end-user friendliness and usability, but that it lacked the much more mature technical implementation that Drupal could offer. I made it my personal battle plan to set up an installation profile for Drupal, developing any missing modules in the process, to bring the best possible multi-user blogging platform both in terms of usability and technical stability. I dubbed it DrupalMU.