I didn't manage to make it all the way through the book, although I might force myself to read the last 30 pages (I mean, I made it through the first 270). It's a boring book about some interesting ideas about language. It begins with a step by step description of how children acquire language by setting out the grammatical structures both inherent and learned in all spoken langauges. This leads to what I believe is the author's main point: that because we all have, underneath our many dialects, the same basic "language" underneath, at least in a neurological sense, then we should respect all other human beings' ways of speaking. There is a large section comparing and defending African American English to Mainstream American English, with arguments made elsewhere, such as how the double negative is apparent in many romance languages. It's an interesting and important point, but somehow the tone manages to come across as a little patronizing, despite the fact that I think Roeper feels passionately about the topic. Perhaps it's the stodgy way in which phrases from different dialects (in British English, AAE, MAE) are placed on the page and picked apart by someone who has clearly never actually said any of them out loud.
Overall, the book feels a little stuck in going over minutae of grammar in children, while contrastingly making sweeping generalizations about human beings without going into enough (for me) depth with any particular claim. I'm glad I read it, but I didn't enjoy it.