Overall, this is a very good movie and worthy of the good reviews it has received in the media. As far as a review for your children, the online video review provided by this site is quite good and gives an excellent overview of what to expect. For the most part, violence is the area of concern in this movie. There is quite a bit of violence and agression, with most of it being between humans and apes and some of it between apes and other apes.
My 10 year old son and I watched and enjoyed the movie. There were a few scenes that were a little intense for my son and he mentioned that he was "a little" scared. Before the movie, we talked about the story being fictional, that it was just a story. I think the differentiator on this movie, compared to things like Avatar and Harry Potter, the setting is modern day and the plot is explained with modern technology and science. This may make the story line a little more believable for children compared to those other movies where imagination is clearly behind the ideas.
There is a lot of opportunity to have parenting conversation with your children. Animal cruelty and greed were high on my conversation list. Conversations about acceptable treatment of animals took place. We also talked about how greed can cloud judgement (big corporations wanting to make money in this case). Finally, we talked about how humans have a history of altering the balance of things in nature and how it never works out as expected.
I really thought a long time about seeing this movie with my 10 year old boy. While I personally believe that this movie is less intense than others he has seen, such as the Harry Potter movies, I think the change of setting is the real difference in this movie for it being more intense for a child his age.