The answer depends on if you prepend the sub name with & or not.

If you do something like &blah, the sub gets the current contents of @_ as arguments (it's equivalent to blah(@_)).

If you just do blah, then if the sub's been predeclared, it'll be called. Otherwise, it's interpreted as a bareword string. Which is probably not what you want.

I avoid the controversy altogether by using the parenthesis as often as possible, and the ampersand only when dealing with references. I haven't found a good use for &blah, passing @_ by default, except for certain AUTOLOAD routines. It's better to avoid side-effects that might confuse someone else reading my code.

They'll be confused enough already. *sigh*