NetBeans is slick. I just finished a small java/swing project to make a desktop data conversion tool. I don't have much experience with java and almost none with IDEs but I was pleasantly surprised.

I found the editor to be decent and had good emacs bindings, even enabling the "tab goes to proper indent" behavior. The debugger was very good. It was able to easily manipulate the various threads of the program and quickly find a problem. The build files that NetBeans generated were well designed and I was able to easily add some build actions.

My only other experience with an IDE was visual studio in 2004 in my freshman c++ classes. That was huge pain. Nobody really understood what it was doing. And problems were regularly solved by creating a new project and copy-pasting code from the old to the new. On the other hand VS may have been great and it's the additional 10 years of experience that made the difference. haha