Recs.
Updated
Fully featured IDE with both a free community edition and a paid enterprise edition. Jet Brains prepackages this open-source development environment with loads of capability.
SpecsUpdate
Pros
Pro Capable of doing everything
IntelliJ IDEA feels like a breath of fresh air after fighting with the likes of Eclipse. Every kind of project you can work on, from Enterprise Java, to web-dev, to simple scripting and small application creation, it has been very enjoyable to work with.
Pro Smart refactorings
IDEA places an emphasis in safe refactoring, offering a variety of features to make this possible for a variety of languages.
These features include safe delete, type migration and replacing method code duplicates.
Pro Intuitive and slick UI
IDEA has a clean, intuitive interface with some customization available (such as the Darcula theme).
Cons
Con Depending on your project, set-up can be challenging
IntelliJ is what you make it. It can do a lot for you, but sometimes that takes a little bit of configuration and set up. If you're working with a VCS or any project with a plethora of dependencies, you need to make sure you've got everything set up right first before you attempt to get going on your work. IntelliJ behaves though once you tell it to do so. Good thing there is also plenty of documentation.