Show on little more than 100 pages of Strunk & White the reader how he can improve the quality of written texts with simple means. The advice is not directly transferable to the German language, but this is not a problem: In research and business English is the predominant language.
The book is not addressed explicitly only to writers, as well as knowledge workers, students, researchers, programmers, engineers or bloggers benefit from this small masterpiece. Anyone who has to write more than 10 lines, whether technical documentation, scientific papers or project-related emails will quickly notice an improvement in his style.
Of course, this is not an end in itself: The reader is given as a better access to the work and you yourself will have more pleasure to read and to expand its own products.
In short: a recommendation for everyone, absolutely everyone, the professional or training related that wants to submit a document or other in English.