SCWCD has its focus on Web Development.
Preparing for the exam will take you through a typical request response cycle in J2EE. It will also take you through the concepts like filter and web deployment including security features.
Whether you take the exam or not; preparing for it and studying can easily help you build a web application.
"Head First Servlets & JSP" is a nice book that keeps you interested with its interactive interface and describes basics very well.
I have studied this book; however i'm not a SCWCD; so can't say about the weight my advice carries
All the Best !!!
Passing the exam needs very good knowledge of JSP and Servlet API. With the help of these APIs you'll be able to develop not just website but great web applications. Preparing for the exam gives you advantages like:
1. thorough knowledge of Java APIs for the web applications
2. if you pass the exam, that means you have proven skills in the above areas
3. you can troubleshoot many issues related with Java web applications and gain respect from your colleagues, friends and your employer