This is one of the most often quoted commentaries on the Book of Daniel. It has less information than Montgomery's commentary, but is more readable. Hartman and DiLella are often quoted in Bible dictionaries, encyclopedias, and other commentaries.

They include an unusual new translation of Daniel influenced by H. L. Ginsberg. Ginsberg believed strongly that Daniel was originally written entirely in Aramaic, and that this fact is betrayed by confused translation from Aramaic to Hebrew in the Hebrew portions of the book. Hartman and DiLella try to reconstruct the original Aramaic meaning by stripping away errors in translation.

The commentary has a lot of discussion of the "son of man" (or "one in human likeness.") It comes to the conclusion that the "son of man" originally referred to faithful Israel and didn't have a messianic meaning. The authors believe the messianic connotation derived from later apocalyptic literature (the Parables of Enoch and II Esdras.)

The commentary frequently cites Jerome's Commentary and Porphyry. They seem to be at ease with Latin, which isn't surprising for Catholic scholars.

Aside from the examples above, most of the explanations in the commentary are reminiscent of earlier commentaries like Driver's and Montgomery's.

Besides the fact that it's respected among scholars and frequently quoted, I think this is a good deal for the price.

I like it more that Di Lella's more recent commentary.