As has previously been said, I found Vaughan a joy to watch when he was in form. His tour of Australia in 2002/03 was obviously the pinnacle of his batting career. The ease in which he picked up the fairly short ball, and drove with absolute impunity, indicated he could go on to become one of the very finest Test batsmen of our time.
Unfortunately, imo, he probably did not reach his full potential, injuries, long spells out of form, the weight of captaincy on his shoulders, all played their part in making Vaughan an under-achiever, when you consider the amount of talent he possessed.
His captaincy was outstanding, the way he led the side, and the tactical side improved as he did the job. A top player for England, if not for Yorkshire, but in a different life could most probably have achieved much more.