DW and I absolutely loved this movie. Freeman was superb as Mandela. He had the mannerisms and the accent down pat. But even more, he conveyed the sheer dignity and power that radiates off Mandela.
One of the best things about the film is that it does not focus solely on Mandela (or on the character portrayed by Damon), but shows the impact of the changes in South Africa on a whole range of people, from several members of Mandela's staff, to a small child about your son's age, who despite his bit part almost steals the movie at the very end. Among the funniest moments come near the beginning of the movie, when the security detail protecting Mandela has to be expanded; watch what happens in the interaction between these people throughout the movie.
The many scenes of South Africa, and the way music is used, is also great.
I think the movie would be perfect for an 8 year old, and it will probably make him (and you) want to visit South Africa. There are no sex scenes and - aside from the action in the rugby scrum (do I have the terminology right?), very little in the way of violence.