At Lecando we are long time licensees of IntelliJ IDEA. But since Eclipse is free and open source is good, I have given it a serious try in my spare time. After 2 months I’ve returned to IDEA. Much faster, more intuitive and less weird views of everything (“Do you want to switch to the Java view for your Java project?” Uhhm … yes?). As Jon once said: Eclipse is bloat, IDEA is not.
Eclipse strongest points in my view are incremental compiling and a nice JUnit integration.
The worst part though: it is slow. Really. If you’re an Eclipse user and don’t agree, try IDEA out and see for yourself.
Also, I find it not really focused on what is trying to do. It is a Java IDE, but with it’s micro kernel architecture it can also handle your PHP, Python, Ruby and it can be that IDE toaster oven you always wanted. But editing anything else but Java is done in a very basic fashion. JEdit does IMO a better job of being your versatile handle-everything editor.