" The article also didn't show consistency with the outline and the actual progress of the user. It doesn't highlight the specific section on the outline (left side) so the user will be at a loss when he takes a break and return to the article a few minutes later. Of course, there is the page progress on the upper right corner but this is not a very useful progress indicator and very inconsistent with the outline. There is also some inconsistency with describing the steps and showing screenshots. In some sections, there are numbered steps (ex. "Data Form Searches") while bulleted steps in some (ex. "Excel AutoFilter"). Some sections also lacked screenshots where these were most needed. This is particularly applicable to the "Advanced Filters" section, where mistakes are mostly likely to happen. One other glaring usability issue is...

In the "Introduction" section, there's a link to another web page displaying the database. The user is required to select everything then copy-paste to Excel. Wouldn't it have been easier just to provide a link to an actual Excel file where the data is already present?
The article shows a fairly good attempt on instructing the user on how to use Excel's filter functionality. It showed the basic steps and eventually led the examples to advanced scenarios. Although the article is pretty good, this isn't the one I would recommend to colleagues. I would probably search for better-written articles.

References

Learning Link Finders, Inc. (2008). "How to Filter an Excel Database." Retrieved May 11, 2008 at http://www.docnmail.com/ExcelFilter/filter1.htm