The main topics include characterization, point of view, dialogue, and monologue. The book definitely skews toward the micro end of the editing spectrum; there’s not much discussion about plot structure, thematic development, or putting scenes together. But that’s fine. What it does it does very well.
One especially nice thing about Self-Editing is that each chapter ends with some questions you can ask yourself during the revision process. It also includes exercises (and even sample answers in the back), which I wasn’t especially interested in, but would come in handy if you were using the book for a class or workshop.