Dr. Walton's work is well worth reading. As one reviewer suggests, background material is very helpful in shedding light on the text and meaning of the Old Testament. To be fair to Walton, however, requires a more thorough explanation.
Walton's general thesis is that the comparative method can help readers understand the Old Testament better because it helps put us in the place of the original author/audience. While there was an effort earlier in the 19th and 20th centuries to point out only the similarities between texts or only the differences, Walton's approach is similar to that of William Hallo or Lawson Younger; namely, to think through both the similarities and the differences between ancient near eastern texts and the OT biblical canon.
What is particularly helpful about Walton's book is that the material is arranged according to genre. The following genres are covered:
cosmology (trying to understand the ancient's conceptual worldview)
covenants and treaties
hymns, prayers and incantations
By grouping various ancient texts in this fashion, it provides the reader with a well organized approach and makes using this book as a quick reference very helpful. Each chapter contains an introductory piece on the literary genre, followed by a brief but thorough listing of ancient texts that fit into this genre from Egypt, Canaan and Mesopotamia (absolutely replete with bibliography), concluded by a discussion of the texts and what kinds of insights can be given into biblical texts. It is a trustworthy evaluation because Walton is a faithful evangelical as well as a rigorous scholar. It is important to note that he points out both the similarities and differences. In recognizing similarities, he doesn't suggest gross borrowing, as some in the past suggested, but rather that the biblical material is given by revelation from God into a cultural context that could appropriately understand and receive God's revelation. In this way he upholds the authority of Scripture. Furthermore, he demonstrates very significant differences between the ancient near eastern literature and the biblical corpus such that it becomes increasing clear that the OT functions in different ways we normally wouldn't recognize: polemically against ancient cultures; demonstrating the LORD to be unique and holy compared to other deities; and revealing how extraordinary it is that the LORD, his character, ways and will can be known by the Hebrew people.
Another highlight is that the reader will learn a bit about the comparative method as well. Walton always takes into consideration the following important factors:
Are the texts to be compared of the same genre?
Are the texts to be compared talking about the same subject matter?
Are the texts being compared geographically close enough to suggest an influence one way or another?
Are the texts being compared close enough together in time to be compared?
These are important questions to ask and can go a long way in helping anyone think through many of the crassly alleged cases of "borrowing."
A particular highlight for me is the section on hymns, incantations and omens. Here the reader will be introduced to Mesopotamian laments, for instance, that show that the Mesopotamians had little way of knowing how or if they had offended a diety. You compare that with Psalm 51, for example, and you begin to appreciate all the more how gracious and extraordinary the LORD is who has revealed himself to his people in a discernable and trustworthy way such that they can knowledgably approach him in prayer, repentance, worship or whatever else.
Also, the chapter on treaties and covenants is very helpful in addition to a work like Craigie's commentary on Deuteronomy where the Hittite vassal treaty has long be seen to be parallel to the form of Deuteronomy.
Finally, a very helpful Summary and Conclusions chapter helps bring the material and conclusions together in a neat and summary fashion that is especially helpful for reference and general review.
I recommend this work for the more serious student of the Bible to fill in a crucial and sometimes overlooked area of biblical study and for the seminary or graduate level as well.