I switched a year ago and the usability improvement is substantial. This isn't vim vs. emacs, this is emacs vs. MS Wordpad. Is it perfect, no, but it is so much better than Eclipse. Eclipse is one tool for all jobs which makes the UI very clunky and not very intuitive. Even C++ developers on our team when switching back and forth between Eclipse and Visual Studio (we do cross-platform development) would loath at their time using Eclipse. I used to defend it, but not any more. Sure, maybe this will turn into an Android vs. iPhone debate, but let someone use IntelliJ for 6 months (after having experience with Eclipse) and tell me how many people want to switch back.