Installation is a simple matter of unpacking and enabling the module. There is an administration screen which controls whether the editor is enabled by default, and controls use of the IMCE plugin.
WYMeditor is subject to the issue described here: Conflict between WYSIWYG and Line break converter However since it's possible to easily switch out of WYMeditor this isn't as big a deal as with the other editors. WYMeditor can be configured so the user must explicitly switch into the editor. Or it can be configured so the user can easily switch out of the editor. In either case this allows the user to edit in either HTML or WYSIWYG modes pretty easily, allowing the user to easily edit content in Drupal's traditional format (using blank lines to mark paragraphs) or edit content in HTML format.
The editor supports a small but useful subset of the HTML markup. The authors of WYMeditor have apparently put strong emphasis on generating correct XHTML, and certainly the code it produces is clean.
The editor is relatively functional.