I am determined to write at least one Rails application. Obviously there must be something to it, otherwise it would not have so many fans. I just wrote that rant because I was kind of frustrated with Rails - sometimes aesthetic issues are hampering my productivity. I would be curious how many excellent Java developers have switched to Rails happily. Your example doesn't convince me very much, because of the GWT ingredient. I haven't used it, but the concept sounds very weird (compile Java to JavaScript), so I am not surprised that you gave up on it.
Give it a shot for your own edification - a lot of making a rails app is the command line: install ... The lightweight plugins are just beautiful, and they would only be possible with Ruby or a language like it. It really makes your code a joy to create, maintain, and update.