"Pirke Avot" (the "Chapter of the Fathers") is a tractate of the Mishnah that collects not laws but sayings of the tannaitic Rabbis, mostly concerning the virtues of Torah study and the proper conduct of scholars. It is one of the classics of rabbinic literature, included (in whole or in part) in most prayer books, and the source of many familiar sayings. The picture it presents of Torah study as a democratic ideal, available to all and instilling a generous humility and respect for others, is a goal we can still admire and aspire to.
The translation and commentary presented here is helpful but leaves something to be desired. Each passage of Avot is followed by a brief commentary, generally identifying the rabbis quoted, providing some quasi-historical background on them and their relationship to other quoted rabbis, clarifying obscure phrases and summarizing the thoughts of Rashi, Maimonides and Bartinoro on many of the passages. (The introduction might lead one to think that the commentary also summarizes "Avot de Rabbi Natan" and Yom Tov Lippman Heller's commentary, but I found only a few references to either of these works.) This commentary is very helpful for understanding the plain meaning of the text, but seldom goes beyond the plain meaning to explore the theological or ethical significance of the passage. (A few passages that make the Reform editors uncomfortable are noteable exceptions -- here the commentary notes that "we modern Jews" look at things differently. While I agree with the modern conclusions, I found this condescending attitude annoying and unnecessary.)
Each chapter of Pirke Avot is followed by a section of brief essays (usually two or three paragraphs) by the editors on "salient themes." These often seemed more tangential than salient to me (a brief statement in Avot 3:1 that we return to dust leads to an essay on Jewish views on cremation), but they were interesting and provided further background on various aspects of traditional Jewish history, practice and thought. The brief essays are followed by section of somewhat longer "gleanings" from the works of various Reform or liberal Jewish thinkers. These tend to be quite tangential and are plainly intended to provide food for thought and discussion, not to answer questions. A few of them seemed more than a little out-dated, but in general the selection was interesting, if obviously slanted toward a Reform view of the world.
A final note on the translation, which is colloquial and inclusive. The former (particularly the use of contractions, which to my ear made too many passages sound like "don't be a don't bee") was irritating to me, but that's a matter of taste. The attempt to be inclusive (i.e., to use gender-neutral language), however, led on more than one occasion to translations that were so awkward they were a distraction ("everyone has one's moment"), which I find more difficult to forgive.