As faculty, you assess textbooks against a set of criteria that reflects your long experience and knowledge of student needs. You do the same with Open Textbooks, but there are a few additional considerations.
This is an introductory textbook in logic and critical thinking. The goal of the textbook is to provide the reader with a set of tools and skills that will enable them to identify and evaluate arguments. The book is intended for an introductory course that covers both formal and informal logic. As such, it is not a formal logic textbook, but is closer to what one would find marketed as a critical thinking textbook. Downloadable as a pdf file.