I'm enjoying Barraclough's book, but the potential buyer should be clear what it is and isn't.
Starting in the year A.D. 800, Barraclough traces the political development of Germany, and the book is indeed excellent for its handling of the early Holy Roman Empire, the Investiture Controversy, and the rise and fall of the Hohenstaufens.
The accession of the Habsburgs inaugurates "the Age of the Princes," which the author treats with a jaundiced eye. The unstated assumption is that Germany fell behind England and France by failing to come together as a unified state.
Then one gets 100 pages on, brace yourself, 1519 to 1939. (The book was published just after WW2.) I haven't gotten there yet, but it seems safe to guess that the treatment will be on the cursory side, presumably with an emphasis on the continuing repercussions of the medieval background.
So I would hesitate to call this *the* book to read on German history. Holborn's 3-vol. survey is probably better, but Barraclough's incisive analysis makes this a good one to have for the earlier period.