I received my copy yesterday, so here's a little more detail.
The catalog is indeed thin. Here it is compared to a new copy of Vol. 1 of the 2021 German-language Specialized that came in the same package.

In keeping with Michel's standard format, it's hardcover with the little bookmark tassel attached.
The first 20 pages or so contain Michel's standard introduction to its English-language catalogs, so new users can understand Michel's cataloging system.

The catalog contains the basic, non-specialized listings for Germany 1872 to 1945, as well as officials and booklets/booklet panes/booklet se-tenants.
Page counts are roughly as follows:
German Reich -- 63 pages
Officials -- 9 pages
Booklets -- 17 pages
By comparison, these page counts in the English-language Specialized version are:
German Reich -- 150 pages
Officials -- 18 pages
Booklets -- 84 pages
The listings appear to be verbatim translations of the non-Specialized German catalog (Michel
Deutschland 2021/2022). The colors are significantly simplified from the Specialized, though this is in keeping with the basic nature of the listings and the same practice in the equivalent German version.

One thing that is new is the inclusion of color references in the listings. Note in the pages shown immediately above, the color reference next to each listing -- ex., for MiNr. 651, (11,13,8). This is a reference to the basic color (11), admixture (13), and saturation degree (8), and it serves as a cross-reference to the Michel Color Guide.

At the moment, this is of somewhat limited value, as the catalog listing is more detailed than the Michel Color Guide. IOW, many of the colors listed in the catalog aren't in the color guide, though a very closely-related color likely is. I think there's a new Color Guide coming soon, so we'll see if this is an indication of what to expect. These color listings in the catalog are NOT included in the German-language catalogs, either Basic or Specialized (even the just-arrived German-language Spezial 2021), and aren't in the previous English-language Specialized either -- this is the first Michel catalog I've seen them in.
There are a few formatting issues in places. Michel notes in the Intro that, due to a new production process, there are minor formatting inconsistencies that couldn't be corrected by the production date -- not really sure what they mean by that. They further state that the issues will be fixed with the next volume in this series, the English-language West Berlin 2021 catalog.
The main one I noticed is in the inflation issues of 1923. In its previous catalogs, Michel has used a two-column format for some pages, and a one-column format for others. This allowed them more room to work with when the listing called for it. In this catalog, they went two-column throughout, and it just doesn't work for some listings. Compare these listings from the basic German (left) and new, basic English (right) catalogs.


Overall, though, it's a good catalog for what it is -- a basic Germany catalog for English-speaking collectors. If you don't want to fight through the language barrier and aren't interested in a Specialized level of detail, it's the best option out there.