Arguably one of the most convtroversial philosophers within the Continental tradigion, Derrida's work either heralds a revolution in philosophy or its utter destruction.
Derrida cites two important pedigrees (as the title suggests): Husserl and (tacitly) de Saussure.
Using the "course in general linguistics" of de Saussure, Derrida notes a certain degree of freedom, a "jeu," between the words-as-symbols and the thought contents they produce. Exploiting de Saussure's note that the relation between the sign and the mental content is arbitrary, Derrida questions the validity of any text (where the notion of text includes, but is not limited to, books, magazines, commercials, art, sex).
Derrida sees behind any "text" its entire recursive history, the weight of all the words, the mental experience of the reader.
At the point he considers the reader's experience he starts to deal with phenomenology - the study proposed and defined by Husserl himself in his Vienna and Paris lectures. A short definition might be that Phenomenology is the study of how man mentally relates to the objects of his experience(I admit, debatably so).
This book proposes Derrida's famous example of "différance" and its effect upon the Gallically trained ear and mind. So if you want to seem witty and "with-it" this introductory tome shall suffice.
As far as my own deconstruction / critique of the work. As an introductory work it is dense. Derrida is often criticized for losing himself in intellectual crevices, being prolix, and employing poor stylistics. These are not unmerited. Yet for the reader who wishes to move beyond the fashionability of tossing "deconstructionist" out at cocktail parties, this is a must read. It is certainly part of the 20th century canon.
My own conclusions are mixed. In his later works Derrida becomes truly absurd, laughable, silly, and occasionally brilliant. Yet his work never fails to move its readers either to agree that he is either an idiot, a bad writer, or that philosophy as we know it has long been dead. Perhaps like a Socratic gadfly, Derrida is moving us to an entire gestalt shift vis-à-vis our relationship with philosophy and social institutions.
A solid background of Kant/Hegel, as well as a familiarity with lingustics (the aforementioned course in general lingustics of de Saussure) greatly ease the difficulty in penetrating his work.