The patterns in this book are as relevant today as they were when Fowler wrote them out 14 years ago. You'll find these patterns used in most of the popular (regardless of language) web development frameworks use today. I've owned this book for 7 years and I reference it often as I plan and build enterprise architecture. I came here specifically to write a review after pulling the book down to plan out a new application. To use a cliche, it has stood the test of time.
I read in a review that this book is biased toward java: I must disagree--while most of the example are in java (chosen because its a language most developer, at least, know how to read, if not program in), the concepts are universal and can be applied to almost any object oriented language. I've never programmed an enterprise application in Java--yet, it is my go to book when designing architecture for my language of choice.
So if you are thinking are buying this and think it is dated: Its not. Or think its for java devs: its not.