This book is good if you are new to studying Aquinas, but considering in the inreoduction Kreft suggest not skipping the objections and reading the "on the contrary" and the "I answer that" first, he certainly edits many of the articles this way. It is my opinion that Kreeft cut out too much text.
Summa of the Summa (hereafter SS) is a simply wonderful abridgment of Aquinas' Summa Theologica (hereafter ST). Professor Kreeft has done a superlative job of assembling those parts of ST that will be of most interest to readers new to Aquinas' thought. The text is drawn from the Dominican Benzinger Brothers translation of ST, still the most faithful to Aquinas original language and still the most widely available complete edition of ST in English. Kreeft includes a fine glossary of technical terms in ST likely to be unfamiliar to most readers, and a short, readable introductory essay that gives an interesting discussion of the structure of ST. Rather than include a lengthy introductory commentary on the classic text as do many editors, Kreeft includes his comments in footnotes, which appear frequently and are quite extensive. To give one example, to accompany Aquinas' famous "five ways" to prove the existence of God on pp. 57-70, Kreeft provides approximately eight pages worth of footnotes. The footnotes that discuss Aquinas only are nearly always illuminating, and will prove invaluable to readers as they study the primary text. I believe readers of SS will be able to progress more smoothly to the complete ST if they so choose than they could with any other abridgment of ST or other anthology of Aquinas' writings now in print. At the same time, SS is a fine, self-contained introduction to Aquinas' thought.
The only disappointing aspect of SS is its discussion of philosophical positions that are at variance with Aquinas. Like many philosophers working in Roman Catholic institutions, Kreeft has a tendency to present false straw-man interpretations of philosophers whose conclusions he disagrees with, and then to "refute" these philosophers by kicking down the straw men. (For the record, I am Roman Catholic.) For instance, on a footnote on p. 522, Kreeft erroneously attributes to Hobbes the view that people are naturally vicious and to Hume the view that knowledge is nothing other than the passive reception and ordering of sense impressions. Kreeft strongly hints to the reader here that Aquinas' own positions are more cogent than those of Hume and Hobbes, but this is misleading since the footnote presents a "straw-man Hobbes" and a "straw man Hume". Kreeft's tendency to misinterpret and then unfairly dismiss certain important philosophical doctrines even leads him to occasionally misrepresent Aquinas. For instance, in a footnote on pp. 430-431 Kreeft claims that Aquinas' example on these pages refutes utilitarianism. In fact, the classical doctrine of utilitarianism as John Stuart Mill and Henry Sidgwick formulated it is designed to show that the very example Aquinas gives is a CONSEQUENCE of utilitarianism.
In summation, readers can profit immensely from a careful study of the classic text and supplementary materials in SS, but they should take care not to trust anything said here about philosophers who disagree with Aquinas at face value.