The Last Colony is the concluding novel in Scalzi's loosely-connected SF trilogy that began with Old Man's War and continued with The Ghost Brigades. From the start, the novel is fast-paced and fun, and fans of the series will be pleased that the new book focuses on two of the main characters from the previous books -- John Perry and Jane Sagan.
The premise of The Last Colony revolves around Perry and Sagan agreeing to run a new colony for the Colonial Union, in defiance of an alien confederation called the Conclave that has forbidden the creation of any new unauthorized colonies. Political subtext and many twists follow as Perry and Sagan discover that the Colonial Union has not told them the truth about their colony, the alien Conclave, or their chances for survival.
As a big Scalzi fan, I was happy for another book in this series. I'm not sure how this book ranks with the first two or even how well it stands on its own. I know I didn't like it as much as the other two books, but I certainly enjoyed it and read it compulsively through two days. I guess, ultimately, if you like Scalzi's SF, you will almost certainly enjoy reading this, even if you don't rate it as the author's best work.