First, let's talk about what John Baylis' "The Globalization of World Politics" is: a sweeping, relatively comprehensive overview of the field of International Relations. With five chapters on world history, another 7 on the major theoretical schools of IR, and then another 15+ chapters on various topics of importance such as international ethics, modern warfare, peacekeeping and diplomacy, international political economy, and others. Suffice to say, GWP is a massive, sprawling look at just about all the major topics in contemporary IR.
That being said, the depth of each topic necessarily can't be more than an overview, and while this may suffice for an "Intro to IR" course, it won't leave you with much beyond that. In addition to that, the strength of each chapter varies wildly; while I found his chapters on realism, constructivism, and Marxism pretty descriptive, sections like those about the impact of post-colonialism or feminism were largely lacking. However, Baylis wins points for having 5-15 "Further Reading" suggestions at the end of each chapter and topic, which serve as a basic jumping-off point for motivated students. He also includes a rather excellent Glossary at the end of the text, which prepares readers with precisely the kind of vocabulary needed to navigate a field as academic as international relations.
Baylis also takes an approach largely agnostic from bias; while you can tell based on his attention to detail about certain topics where his expertise lies, he also largely avoids the very common trap of completely neglecting heterodox schools of thought or uncomfortable facts about popular perspectives. Perhaps this is due to his European academic heritage. All I know is, I was genuinely surprised to find an entire section about Antonio Gramsci's contributions to IR written without bias-- this is something you'd never find from a professor at, say, the University of Texas, and I found it incredibly refreshing. Ditto for Baylis' asides on the spread and growth of economic inequality as a side effect of globalization and interdependence, for another example. Really one of the strongest aspects of the book.
"The Globalization of World Politics" suffers from the misfortune of trying to introduce students to a gigantic and relevant field of study, and while it mostly accomplishes the goal, it can't possibly get all the way. I don't hold it against Baylis, because this effort is sure the best one I've come across so far, but it is what it is. If you're looking for an exhaustive, 2000-page tome that covers every aspect of IR in depth, I'm not sure it exists. But for an educating and interesting introduction? GWP has you covered in spades.