Whether it makes sense to use such an old book depends on what you want to get out of it. As an introduction to the inner workings of servlet containers it's probably fine. If it's specifically Tomcat you need to know about, you're likely better off reading something newer, as Tomcat 5 is long obsolete.
I thought that was a pretty good book when I read it a few years ago. I think Budi is a good writer and he did a really good job in that book. But Tim is right, it really depends on what you want to get out of it. If you want to get information that's relevant to the current version of Tomcat, you may have to pick your way through the current version's source code to see how much of it still matches the material in the book. If you just want to learn about the design of a web container, there's still a lot of foundational stuff that you can learn from it.
Come to think of it, I really liked Java Server Side Programming by Mukesh Prasad. It builds a servlet container step by step basically out of nothing. Even though I already knew servlets and JSP inside out, I thought that was a really good educational approach to teach what's happening under the hood (even though the resulting server doesn't correspond to any existing server).