IntelliJ is expensive. IntelliJ makes refactoring simple. For example, we got acquired by a company and were forced to rename our com.origcompany to com.newcompany. In one project that was several thousand class files. IntelliJ did it in about a minute. Eclipse crashed somewhere after twenty minutes. I actually had to use Eclipse because Flex Builder would only run on Eclipse Ganymede. I lost many minutes of my life waiting for Flex Builder to build. I don't know if that was a consequence of Flex Builder's mxmlc performance but I do know that Eclipse completely froze on our Windows machines a few times a day. For a team trying to get a app done, we unofficially acknowledged that Eclipse was an impediment. The major drawbacks to IntelliJ is that Git support is poor. I would recommend just doing stuff from the command line for Git. We use SVN. My general feeling with IntelliJ is that it is a very polished product that I've been using since 2000 (before that we used the awesome Visual Slickedit). In Eclipse, I found that simple stuff that you may do often isn't optimized (for example, reference or string searching) - in IntelliJ it is cached. In Eclipse, searching always took forever (I should have attempted to look for a searching plugin). My best analogy is that IntelliJ is a BMW and Eclipse is a minivan. Both work, one is better performance and more tuned. One is feature rich.