For my own reference, I'll put comparisons of Eclipse vs IntelliJ. I didn't like Eclipse because I found setting up projects a pain so it was a bit of a non-starter.
Tom's guide: "Eclipse requires you to save all the time...Eclipse has serious usability issues in graphical diff...Like Word, Eclipse wants to own your files and wants you to make all your changes through it".
It's subject of a recent Slashdot article.
It'd be good to find a comparison of the refactorings that are missing/different in Eclipse. I'm also trying out NetBeans 5 to see what it's like.
Update: An old comparison of Eclipse and IntelliJ and a PDF comparing RefactorIt, Eclipse 3.0 and IntelliJ 4.5. A list of new refactoring in NetBeans. Eclipse 3.2 M4 reproduces many features of Swing and IntelliJ IDEA, one of the threads Is $500 really alot of money?.