Well, its pretty good for the movement but it doesn't really do anything for the timing because it doesn't teach you how to read when the shot is coming. I can't look at a fist and judge when to slip it by reacting when it moves, I look for things like the other guys range, the position of his shoulders and feet etc knowing where he is and where he will be once he starts to move is how you time a slip

The fist is the last thing to move in a punch.