Not sure if this article has been linked but it has more pics of Tom as Walt.
FIRST LOOK: Tom Hanks as pioneering animator Walt Disney in Saving Mr Banks | Mail Online
I agree that Tom is not a 'ringer' for Walt Disney, but I think there are plenty of movies where an actor only has a slight, if any, physical resemblance to the person they are portraying, real or fictional. But if they are able to nail their mannerisms & speech patterns with the right hair & makeup they can be pretty believable. I think Tom Hanks can pull it off. After all, we all loved and bought him as Forrest Gump, didn't we? Lord knows he doesn't resemble the Forrest in the book.