Can I rely on this book to learn Servlets and JSP,or is there a better book out there I should be reading instead?
You might want to try the Head First series by Bert Bates and Kathy Sierra. They're particularly geared towards being brain friendly (e.g. Easy to digest).
JEE is a vast area, hence, can't be included in a single book. But, to learn about JSPs and Servelt, you can follow K&B's Head First JSP and Servlet book. It's the recommended book for Sun's SCWCD exam.
Oracle covers both JSP and Servlet under SCWCD exam. The exam objective fully covers the advanced concepts so better you may prepare for SCWCD certification exam. It gives you deep knowledge in concepts. In my experience I said it, the certification help me more to go to next level in my carrier.
An excellent material I refer you that one I used for my preparation. I hope this is the only one material enough for your preparation, because it has both study guide and also sample mock exams.
The Exam Objectives are explained with example programs in this study guide so you can easily and quickly learn the concepts. I used EPractize Labs SCWCD 5 Certification Training Lab for my preparation.
For more details read the scwcd 5 preparation article.