An IDE gives you three very useful tools. Code editing. Code navigation. And code debugging. Each of the commenters, I am sure, have different needs and styles of these tools. You will also.
All the IDEs tend to have very aggressive code editing help. This is great when you are working with new packages but the help gets tiresome as your packages familiarity increases and yet the IDE continues to make suggestions when you know full well what you want. Code navigation in modern IDEs is a godsend. To be able to move easily between classes, up and down the inheritance hierarchy, and around usages. Code debugging is less about the source and more about the data and the threads. The better the tools are at showing data structures -- the plural is important! -- and visually connecting threads w/ stack traces the easier your job becomes.
I have not answered your question because there is no answer. We shape our tools and our tools shape us. It almost does not matter which you pick -- Eclipse, IntelliJ, NetBeans, Emacs w/ JDEE, Vim w/ JDE, .... What matters is that using the IDE becomes second nature to you.
And don't fool yourself that you will fix the IDE's problems. You don't have that much free time.
