Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Large gap between problems and explanations in the text

This is my least favorite book on the subject of signals and systems. The book is very wordy, and often explains things in overly simple terms, then presents extremely difficult problem sets as accompaniment. The section on convolution (a very simple concept, really) made my head spin. It's no good to spend three paragraphs explaining something that is essentially 1+1 = 2, then leave the student to do an exercise which is more like a differential equation.