If there is one solid reason to look at the Netbeans 5.0 release, then all the hype I have been hearing is defintely centered around the new GUI builder called Matisse which is included in 5.0.
Matisse has been referred to as the VisualBasic style GUI builder for Java – at long last we have a simple and effective way of being able to build GUI layouts in a simple drag and drop way. Dick Wall (one of the presenters on The JavaPosse podcast), gives an overview in this article on the developer.com website.