I have been using Eclipse for several years now and it has treated me generally very well. There are so many plugins that the only real hassle has been the few occasions where the plugins collide. However, since appetite grows while dining - I have recently come very close to declaring a divorce! Why?
Upgrading to a J2EE project
One cool thing about Eclipse is being able to deploy a web app and debug your servlets, etc. Eclipse knows how to run Tomcat (and others) and deploy your web app to that server. The trick to all this is that your project must be a 'Dynamic Web Project' (in Eclipse 3.3) or thereabouts. Fine. The problem arises when an existing project grows into a web project. No! We're sorry - you can't add the 'Dynamic Web Project'(DWP) facet to a POJP (Plain Old Java Project). No problem - I'll just make a new project that is a DWP. Now let me get the code from Subversion - let's see: run "Team->Share Project". We're sorry, you must specficy a NEW subversion folder. But I want the one that's already there!
[Actually I just remembered there's now something like "Import from SVN"]
Ok - yes, you can create a new project which is "Check out existing project from SVN" AND even run the "New project wizard" on it to make it a dynamic web project, or whatever you need.