One of amazons reviews about the book mentions that it may be a little outdated. Is this true? But there is currently only 1 version of the exam, the 1.4 version, so what exactly does it mean by outdated?
There are three ways to look at the phrase "out dated".
First, HFS is a study guide for the SCWCD certification exam. The exam is still on the servlet and JSP specs for J2EE v1.4. This exam will not be updated for J2EE v1.5 (which is now called "Java EE v5"). This decision was made due to the fact that the servlet and JSP specs are not changing significantly for Java EE v5. Therefore, from this perspective the HFS book is not outdated.
Second, HFS is an introduction to servlet and JSP technology. As such, specs change periodically and a book will naturally become outdated over time. However, as I just stated the serlvet and JSP specs for Java EE v5 will not be changed dramatically from the J2EE v1.4 version of these specs. Therefore, HFS will only be moderately outdated.
Lastly, HFS uses Tomcat as the webapp deployment environment of choice. Open source implementations tend to evolve linearly over time (at least as long as the tool is useful). Therefore, the HFS book has gradually drifted out-of-date with Tomcat. Is that really significant? It is if our instructions for configuring Tomcat has become outdated. However, I suspect that there is little in HFS on Tomcat-specific information. If you want the latest and greatest on Tomcat, then HFS is not the book for you. I would recommend O'Reilly's Tomcat -- The Definitive Guide or the online documentation.
Marzo, I did not see the HFSJ review that you're referring to. Perhaps you're thinking of the "Outdated!" review of SCWCD Exam Study Kit: Java Web Component Developer Certification by Deshmukh and Malavia.