I was disgusted. Not only does Shaw evoke so much more emotional depth in his "performance" - and all he was told during the filming of that shot was to "smile and look happy" - but he just fits better. Luke wouldn't recognize Hayden, anyways.
Plus, Shaw has a warm, fatherly smile - Hayden's creepy glower makes him look like some kind of child molester!
Let's just hope that Lucas doesn't give us any more unwanted "surprises" - like, heaven forbid, replacing Shaw in the scene with Luke with a CGI-pasted Hayden. That would be the last straw.
And I miss unmasked Shaw's eyebrows!! :(