It works with all Ruby objects. You don't have to care about maintaining reference counts in extension libraries. This is better for your health. SWIG interface is also available. If a value is small enough, an integer is a Fixnum, otherwise it is a Bignum.
Conversion occurs automatically.
Ruby needs no variable declarations. It uses simple naming conventions to denote the scope of variables. So it is also not necessary to use a tiresome 'self. Ruby can load extension libraries dynamically if an OS allows. Ruby features OS independent threading.