I'm not going to pretend to be a developer here, and I'll openly admit that the bulk of what IDEA 12 does is over my head. However, I do understand its importance and relevance. Still, for the sake of correctness, we'll keep this one short and sweet.
When it comes to Android app development, there's Eclipse, then there's IDEA. IDEA 12 is, naturally, the newest incarnation of the application, and it brings a slew of new stuff that developers can make use of:
- New interface and "Darcula" theme
- New compiler mode
- Support for Java 8, Spring Framework, and Play 2.0 for Java and Scala
- Android UI designer
- Database Development tools
- ...and more
Like I said - I'm no dev.