At work I have Eclipse and Netbeans open all day every day. Netbeans for the Netbeans RCP app development and Eclipse for the EJB backend. IMO, the Eclipse editor (the actual text editing component) really blows. It’s ugly, buggy, and slow to edit large files (10,000 lines+). Netbeans on the other hand fails to start a managed instance of JBoss because it can’t handle the 25MB log file in it’s console output window (ie this means we can’t debug into J2EE apps in Netbeans probably could by attaching the NB debugger to a running JBOss but no one has arsed about with that).
What it boils down to for a newbie is: in Netbeans everything just works after one download. Eclipse you have to chase plugins down and it’s more work to set up. Otherwise, they provide the same functionality. The point above about plugins for Google goodies is a good one. Netbeans generally has plugins for Google projects like gwt and appengine, but they’re not as mature.
Edit: Another thing is gui builder: Netbeans has long had a very good gui builder in Matisse, Eclipse had no real free option here. Google bought the best commercial Eclipse gui builder plugin and made it free. So now Netbeans gui builder supports only Swing, while Eclipse with Google plugin supports Swing, SWT, and GWT.