It was a fine wrap up to end the story. I am not sure that it can truly be read as a stand alone book (as the author states). You have to understand what Mike and the other characters have suffered up to this book for the emotion to make sense. Great epic end of the World battle. A fitting end for all to be had, the good and the bad.(I did not intend for that to rhyme)
I can honestly say if we had the continuing story of Mike and the 42, I would read that.
If you like monsters of all kinds then this series is a good one to embark upon.