Scheme is a great language for learning, but it is also a practical programming language. Like C it does not supply any output functions in the standard form. But it also emulates a Turing machine in software. I think the parentheses are nice because they help maintain a distinct order of operations. It is also showcases lambda notation (not certain whether that is the correct terminology), which has to do with the parentheses also. MIT/GNU Scheme is probably the most common open source Scheme implementation. Another factor that sets scheme apart which is related is that functions are written in Polish Postfix Notation rather than infix notation. For example, instead of (1 + 2), you would write (+ 1 2), and instead of x = 1, you would write (define x 1). Polish Postfix notation goes like (function left right) or (operator left right).
Scheme has often been used as an ancillary scripting language in systems. One example is The GIMP, which allows extensions to be written in a variant of Scheme they call Script-Fu, which works closely with the GIMP API. Scheme is useful as a scientific tool in my opinion as well, just as C or C++ are.
There is a lot more to Scheme, but there you have it.