A good question asked a few times is, so what's the content of "Beginning NetBeans IDE for Java Developers"? Is it only for those who have never used NetBeans IDE before? How up to date it it?
These are good questions! The book is focused on NetBeans IDE 8.1, which hasn't been released yet, i.e., right now only NetBeans IDE 8.1 Beta is available. An attempt has been made to ensure that all the screenshots (and there are MANY screenshots!) are correct for NetBeans IDE 8.1, while the text, e.g., about the NetBeans Profiler, is specifically targeted at NetBeans IDE 8.1, too.
The book is a pretty thorough tour through all the key features of NetBeans IDE and is useful even if you have been using NetBeans IDE for many years. From the Apress page:
Get the book here, today: http://www.apress.com/9781484212585