Good idea, but I would suggest some ways to improve this to be a more effective Word sampler.
1. Eliminate the many empty paragraphs, many of which are currently just tagged with the Normal style.
Most "best practices" recommend against the use of extra returns for vertical formatting, and for the use of styles other than Normal. For these samplers, I'd eliminate all of the duplicate ¶s (and extra spaces), and use "Body Text" or another suitable style for the filler paragraphs.
(Tip: alter Word Options, Advanced, Display to set a "Style area pane width" so the style names will be displayed for each paragraph in the Draft view. In the Print Layout, the style name is only shown when you click within a paragraph.)
2. Consider including descriptions about how a given style should be used, and arrange related styles to reflect their use.
The use of boilerplate copy works for paragraph-type styles but not so well character styles such as "Footnote Reference" or "Followed Hyperlink". If such styles were shown in context with realistic examples, the sampler would be a better learning tool -- and would more meaningfully reflect real-world changes a user might make to the style definitions.
As well, some styles won't adequately illustrate their purpose with just boilerplate text, and need more for proper context. For example, the descriptive text in your display of each of the "TOC x" styles doesn't include any tabs that would become important for a real table of contents. Your sampler could better illustrate how the styles ought to be used if it included a mocked-up ToC (and set up with a "TOC Heading" above it rather than after the "TOC x" styles).
3. Include intro copy within the sample to provide instruction for how to use Word's style functions to show variances.
In fact you really only need one sampler document, because the Change Styles, Style Set pulldown in the Styles ribbon can be used to change the set to see the other variations. Ditto for the Colors, Fonts, and Paragraph spacing variants within each set.
4. A page layout would allow the sampler to include and show the Header and Footer styles in context and use. (And, per my #2 above, that would be the only way to be able to realistically show section- and document-related elements like page numbering and endnotes.)
Please don't take my observations as being critical Charles; I think the idea is excellent and long-overdue. I've always wondered why Microsoft never bothered to include a well-thought-out sampler document to illustrate the intended use of styles. Had they done so right from the start, I think Word's styles would be far more widely used and understood. With a bit more work, I think a sampler like this could be a very useful tool.