Online genre magazine Strange Horizons has reviewed all four books of the Apollo Quartet. Strange horizons publishes extensive reviews of genre books (and the occasional film and/or television series), so I’m especially happy they chose to cover the Apollo Quartet.
The reviewer is Karen Burnham, who is, incidentally, an electromagnetics engineer at NASA. She writes in her review, “Sales has combined an amazing amount of research and no little literary and science fictional skill into a thought-provoking and thorough look at one of the central set pieces of our modern mythology”.
You can find the review here.
I should also point out that reviews copies of the final book of the Quartet, All That Outer Space Allows, are still available. In fact, review copies of all four books are available, should anyone wish to review the entire quartet. I can do mobi, epub or pdf.