Unfortunately I can not be extremely positive about this work of Ross. Still how you will benefit from the work will depend on your expectations. If you need some summary to draw upon in an undergraduate course, this work will be helpful. But the work will not give you real insight, either because it does not intend it, or simply because it can not achieve it. Sorry that I have to talk like this on a great scholar's book.
Sir David Ross' explication of Aristotle's philosophy is most helpful. Aristotle's works that have survived to today seem to be post-lecture notes, a sort of "here's what I covered in today's lecture" recap. As such, Aristotle's books are sometimes confusing, occasionally contradictory and often just plain difficult to understand. In addition, Aristotle was a scientist first and philosopher second. This makes his works, which we read for their philosophical content, more difficult to grasp in some cases. Further, as with any translated works, various translators convey Aristotle's assertions in different ways, some of them more useful than others.
Ross' deep understanding of The Philosopher, gained through years of study, teaching and translation, gives him the background needed to help the reader understand more clearly Aristotle's position on various subjects. Ross is able to reconcile some apparent contradictions, to point out some of Aristotle's underlying assumptions and make confusing passages clear.
As a graduate student in philosophy, I find Ross' work to be very helpful and expect to use it extensively as background material for my thesis. But the value derived from reading and understanding Aristotle is not limited to students or philosophers, and the value of Ross' book is wide-ranging as well. Aristotle will be helpful to students, teachers or lay readers interested in philosophy but struggling with some of the archaic attitudes presented in many translations of The Philosopher's work.