While there are a lot of things that work the same across languages, there are concepts which are supported in some languages but not in others. For instance when I have to work in a language which dos not have closures, I feel handcuffed. Yet you could have a tremendous amount of experience with C, Pascal, VB, Java and so on without ever having a clue that something like closures exist, let alone how you might use them.

Don't get me wrong. Learning languages is good. If you know several others, you can be productive in a new language once you learn the syntax. However every time you learn a new language you should be prepared to encounter new concepts which don't fit into your previous programming background. It isn't just about syntax.

Perhaps a more down-to-earth example are the many procedural programmers who had to struggle to learn what OO programming was about. A C programmer could quickly write programs in C++ or Java. But they wouldn't be writing programs the same way that someone experienced in those languages would...