From Amanda Murphy's blog, an article about the improvement of the Content Editor Web Part in Sharepoint 2007.
The content editor web part in SharePoint 2003 was very popular – especially for those that wanted to easily add custom static text, images or special scripts to a page. In SharePoint 2007 we see this web part has improved dramatically by addressing a couple of key pain points that existed with the previous version.
The support for tables has drastically improved by allowing for easier manipulations to a table after its creation as well as support for pre-defined styles and formatting. Overall inserting a table in the content editor is a much more enjoyable experience.
Inserting an image in a content editor web part in 2003 was a little difficult for users that may not have been overly technical or comfortable with the concept of linking to pictures stored on the web or in their site. The new improved content editor, makes it much easier for a user to browse to an image stored on their SharePoint site (or site collection) or an alternate location. The ability to change image size on the fly is another positive move.
Remember the styling pains associated with copying text from a document to the content editor? Well the new improved editor makes this much nicer allowing for the on the fly removing of styles and undesired formatting.
You may also recall that inserting hyperlinks in your content editor that were to open in a new window was a task that had to be completed by going into the source editor and adding a target attribute to your link. This has been improved as well by allowing user to specify when creating a hyperlink whether it should open in a new window.
You can find this article here.