Like another reviewer, I also had this book for a course on Byzantine art. For the most part, Lowden's book is a "survey" in the fullest sense of the word: on average, he only spends a paragraph or two on a particular monument, focusing primarily on style and iconography for icon panels, mosaics, architecture, and "minor arts" (always a dilemma when writing a survey book--quantity of material versus level of depth in one's discussion). He also follows the traditional chronological framework of discussing Early Christian/Byzantine art: from the catacombs and the reign of Constantine, to the fall of Constantinople to the Ottoman Turks in 1453.
Having said this, Lowden's book stands out among other surveys for many reasons. Although too numerous for the length of this review, among such strengths are his extensive discussions of Byzantine manuscripts (Lowden's area of scholarly interest), including a chapter on production and reception. He also devotes some attention to the factors surrounding the rise of Iconoclasm, and subsequent artistic production after the iconophiles had "triumphed" over this era of the destruction of figural imagery.
Although a handful of other Byzantine art surveys have been published since Lowden's book (some good, some bad), I feel that this ranks within a small, high-quality group of studies on Byzantine art.