Good observation. All the time I've been using Wings, I've never touched the rotate/free command. And yes, it does seem to behave differently from other 3d programs I've used.
One thing I observed is that rotate free rotates the object relative to the z axis of your monitor. So you could change the view orientation during rotate/free by click-dragging the middle mouse button and rotate the object any which way you want that way. Why would you want to rotate free, though, is a mystery to me .