My coteacher's opinion: this book is more grammatically focused, which is probably why, as complex303 pointed out, the dialogues sound so awkward and formal. The lessons are broken up into 7 periods - listening, speaking, reading, writing, activity "talk & act", activity "do & show", and review.
My school is using the 5th grade book. Both my co-teacher and I can't get the CDs to work. The actual contents of the page won't load >:[ anyone else who's using the 5th grade book running into the same problem?