For me it is complicated. It is not just what goes on during the session but also encompasses the anticipation beforehand and the aftermath. I addressed those here:

http://domina.ms/~domroot/thebuzz/ubbthreads.php?ubb=showflat&Number=2523&Searchpage=1&Main=712&Words=subspace&Search=true#Post2523

One aspect where I am somewhat in agreement with AspX is the sadistic enjoyment of the Domina does add something, the proverbial icing on the cake.