Five up-to-date GMAT practice tests plus a full-length diagnostic test come with answers and explanations. There are reviews of all GMAT subject areas--critical reasoning, reading comprehension, writing ability, problem solving, data sufficiency, and the new essay writing section.
This was a decent study guide. I'm still going through the practice tests at the end, and have moved on to other study guides to help buttress my knowledge. Huge omission in this book : no CD / Computer adaptive test!