Jujitsu is not a "pure self defense system." It is more of a sport. But spanky is right, good self defense should be easy to learn and easy to use, because when the adrenaline dump hits it's almost impossible to sign your name, let alone pull off some spinning back kick to the head. Any style that has you practice set routines "when he does this you do that, then this then that" won't work. On the street there are WAY too many variables to make any kind of routines or katas practical.
If you really are interested in self defense, look up some of the stuff done by sammy franco (
http://www.sammyfranco.com/ ), Geoff Thompson (
http://www.geoffthompson.com/ ), or Richard Dimitri (
http://www.senshido.com/ ). None of this stuff is meant to look fancy, or be a sport, it's meant to save a life.