I wanted a simple Java book to enhance my knowledge of Java programming language. I have tried many times since 2001 to be familiar with Java and write programs idiomatically, but I have never gotten to a point where I can call myself a java programmer. Thats because I never read a complete book, tried the exercises or understood the concepts as well as I should have.
Java Gently comes in to help a reader like me. It presents the concepts of Java pretty well and does not push the complex ideas early. It treats the whole subject "Gently" and conveniently leaves behind some concepts which will be left to the programmer to deal with when the time comes. The concept of inheritance, static methods were presented well. The book presents complete examples as a way to teach the concepts, which is a useful thing. It also explains the concept of multithreading and how it works in java.
It should be remembered that the language itself has seen significant changes since this book had come. It does no go deep in any of the topics, but the breadth wise coverage of the topics should be enough for anyone to write meaningful Java programs, more importantly be comfortable reading and writing significantly large programs and to the modern reader, it will be useful to write Android applications (You will have to understand Java concepts well, if you ever get into android app development). I did not try the exercises in java, but doing parallel online java classes where I am having the benefit of solving java problems, which seems to be best way to gain and sharpen any new skill.