William Hartnell was way before my time, I came to him through videos and I absolutely love his Doctor. He was probably the most complex Doctor. I don't care that he used to fluff his lines (considering he was suffering the early stages of arterioscleroses and had to learn a new script every week for 40 odd weeks a year I think it's understandable). His performance could be amusing, unsettling, charming, cold, or even very moving all in the space of one episode. I think he's very underated these days. This year marked the thirtieth anniversary of his death (in April) and I don't think there was any mention made of this anywhere on the BBCs site.
For anyone interested, other great Hartnell performances can be found in; Brighton Rock, The Way Ahead, This Sporting Life, The Yangste Incident.