Eclipse is independent of development platform . So you can just get plugin for a particular platform you are interested in, e.g. Java,C,C++, even COBOL and just start coding in Eclipse. So as you can see , as the basic IDE features remain same , it takes very less time to just undertand additional features a plugin provides. Plus the Eclipse is a freeware and most of the plugins too are freeware.
From my experience,I can see few disadvantages too like you need to spend time in downloading and evaluating a plugin. Plus the downside of being a freeware is customer support wont be great. And if you are sure , you are going to use only one platform, lets say Java, you are better off with a commercial grade software like JBuilder.
Regards,
Vikram