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With Eclipse WTP, just run tomcat in debug mode for this ;-)

Doesn't work as well as one would hope. I used to do that, but the Tomcat instance still has to spool a reload in order for certain changes to take effect. Jetty in debug mode works extraordinarily well, and JavaRebel makes it even better.

It's really not the same thing. Tomcat will reload the entire web app. JavaRebel reloads individual classes without the need to reload the entire app. Its not perfect, but it has its uses.

There is a bunch of talk about JavaRebel and webapps and yes, there are issues there. But during something like Swing development it can really save you a ton of time. Imagine a complex UI where getting to a particular form takes several steps. With JavaRebel you can save a lot of time not having to restart your GUI and stepping through all the fluff to get to the form you need and see changes. Close the form, let the IDE compile, open the form again.

It's actually quite the same with webapps.

No, it's not. Javarebel has very basic support for handling different framework specific API's and really each framework dev team would need to take the time to really make javarebel work well with it. For Servlet/JSP based web apps, sure, javarebel works as stated. But no one really does that anymore.

The guy actually just went through our FAQ (http://www.zeroturnaround.com/javarebel/faq/) and copied stuff from there with mistakes. I don't think he actually tried using JavaRebel.