Intellij has a few features that I would have a hard time living without. Code inspection is probably the number one feature that is pretty amazing. You can configure it to check everything from warning about null pointers to unused variables to questionable practices (like an assignment in a conditional). When you have a green light, you can be reasonably sure that the code is clean from most basic problems. The autocomplete is the best I've seen in any IDE, and it allows matches on CamelCase by just typing the capital letters and brings up choices based on type inference. The version control integration is also pretty amazing; I think they could sell the change management and merging portion as a stand alone tool that would do really well on its own. Overall, IntelliJ lets me get into a flow with programming by making a lot of the warts of Java melt away. Sometimes it feels like it's almost writing the code for you and you are just giving it some direction. I know that some of these features have been implemented in Eclipse, but the way they all integrate so seamlessly makes IntelliJ a fun environment to code in. I miss these features in other languages that don't have an advanced IDE.