I think that rational guys have made the use of this
IDE very complicated.
You need to connecte to internet every time you start using this IDE. I think any time investment to learn this IDE is just waste.
If you care for open source and inclined towards IBM,
Eclipse is the right choice for you.
IBM has donated the core of the web sphere studio to open source. The cost of this to IBM was 40 $ Million.
Apart from all this, there are various plug-ins available to plug in to this IDE. For example
Tomcat can plug in to IDE for serverlets and JSPs.