"The Apocalypse of John," by Isbon T. Beckwith, was first published by Macmillan in 1919. It has been reprinted several times since. This is far more than a commentary; in fact, the commentary itself takes up slightly under half of its nearly 800 pages.
The "introductory studies" include chapters on the eschatological hope from the time before the Patriarchs to the NT era, apocalyptic literature, the times and the purpose of John's apocalypse, the question of unity, characteristics of John's literary manner, the theology of the apocalypse, history of interpretation of the apocalypse, early circulation and recognition, authorship, and the identity of the Beast. This is followed by a short analysis of the text (the Greek manuscripts) of Revelation.
The commentary itself is a careful verse-by-verse study of Revelation and is written from a classic amillennial perspective. However, Beckwith treats interpretations that differ from his own fairly and with respect.
While good commentaries on Revelation abound, this is one of the best and should be read by every serious student of the book. Even if Beckwith had never written the commentary itself, the first half alone would make it worthwhile, since this contains information not otherwise readily available from a single source.