Truly, after reading this book, you won't ever think about
object-oriented design in the same way. (Maybe a little bit
exaggerating if you are pattern guru). You would be able to solve
specific design problems and make object-oriented designs more
flexible, elegant, and ultimately reusable using these patterns.
These patterns help designers reuse successful designs by basing
new designs on prior experience. The whole design process will be
much faster (without reinventing the wheels) and reliable (with
proven technique). It also increased common communication ground
between designers and developers.
Don't be surprised that you can even make client/server (or
distributed) system out of these patterns (i.e., Observer (Stock
price notification), Command (remote execution), Proxy, etc.) with
minimal efforts, even though the authors claimed these patterns are
not for network models.
I believe every designer and developer would benefit from authors'
wisdom and insights about OOD with patterns. Please do not argue
the sample code is not in JAVA (EXCEPT you don't know JAVA at all
and can not understand what the pattern means, in which case I
think it would make this argument self defeated.) It is really the
concept that works here not the programming language.