Unfortunately, all the talk on here about his eyebrows, mouth, expressions (they are learned anyway), will not convince anyone who believes there is more that a passing resemblance to Hewitt.
Harry's eyes are his own, but have the same slant as Hewitts, in fact every similarity supposed to prove he does not look like Hewitt, proves he does. In the pictures TheTruth put on here many months ago, show, IMO, that he looks remarkable like Hewitt. Taking into account the apparent question over the date Hewitt and Diana actually started their affair, there is every possibilty that Hewitt is the biological father, but Harry will always be Charles' son.