Yes, it depends on what you're learning - and who you are. For me, Ruby is much easier than Java overall. Learning the basics of Ruby is easier than learning the basics of Java for most beginners, and the Ruby environment (APIs, popular libraries, standards) is tiny compared to Java's huge Land Of Acronyms (LOA).
That being said, I agree that learning the details of the Ruby language is arguably more difficult than learning advanced Java. Ruby is easy to learn, harder to master.
Paolo Perrotta, Europe
Author of Metaprogramming Ruby