Indeed, and learning to use a debugger will allow you to gain fluency in new languages and frameworks much faster that the simple, albeit powerful, printf.

I remember needing to learn Ruby and Rails on an existing closed codebase and having the debugger take me right to the core of Rails several times to understand why certain things were done in a certain way in the top level code. This allowed me to get acquainted with internals of Rails and how Ruby's inheritance system much faster as well as the existing codebase that was built on top.