First and foremost, I love this book. It's very well written and it gets its points across in plain English.
I bought this book in October of 2018 and received the 2014 updated version (which I guess just updated some of the Java specific references for Java 8). The code examples are done in Java, but if you know C# (or really any object-oriented language), the meat of the code examples will be easily readable to you. If you have experience with any object-oriented language, then a lot of the concepts will also be very familiar to you. Even when they go into a 1-2 page discussion about a Java specific thing, you can still just view it through a conceptual lens and follow along with the discussion.
There is a good use of humor, pictures, abstract analogies, and concrete examples to help convey the lessons of each chapter and while this is like a 500-600 page book, I burned through it in a single weekend because it was not only insightful and instructive, but it was also a very entertaining read.
If you're trying to learn more about design patterns and incorporate them into your process, definitely add this book to your arsenal. It's great for learning and good for a quick reference guide as well.