I think this is a great book for kids who understand (and want to understand) the racism and prejudice in the history of America, and it can be great for parents to talk to their kids about how society has changed .
There are the concerns of very mild violence (our kids are exposed to much more serious violence much earlier - so it isn't much of a problem), the use of rude slang for African-Americans (this issue needs to be addressed to the kids so that they don't use it around their friends, teachers, etc), and the fact that the rape of a white woman is an intergroup part of the book (understanding rape and the consequences, how wrong it is, etc, may help).
The good points are that the novel contains great role models such as Atticus, who teaches his kids that prejudice, racism, etc is wrong. Scout - who's age ranges from six to nine in the novel - portrays adult issues very well for a naive mind.
Must keep in mind that the language used (1930's slang, pronunciation, grammar, etc), so parents may need to explain some words. But once you get into the style of writing, it'll be interesting to the end.
Give it a go!