I have seen quite a few people adopting the approach of quoting the author's entire story, and marking that up with red and strikeouts, etc. I'd like to make a case against this practice. A review should have a point to make, like any other piece of writing. To do that, the review should be the primary element the reader sees. Then quotations from the author's piece should illustrate those points. If instead the reader must go back to a monolithic block and find the markup that relates to the point you are making, it dilutes your message. Putting you own text together, with selected examples highlighted after each point makes the message much clearer, in my opinion. It also encourages the reviewer to select the things the author is best off focusing on, rather than just laying them forth in the order of appearance.