Two Series and a Hope.
When he came out with a sequel "The Ghost Brigades", I was hopeful that it would be as good as the first effort.
It was. And then some.
While I wait for the third book in the series, I find myself hoping that Scalzi doesn't pull what Colleen McCullough did... with the Masters of Rome series (The First Man in Rome, The Grass Crown, Fortune's Favorites, Ceasar's Women, Ceasar, and The October Horse). After completing the first 5 books, she STOPPED! She worked on other projects and took years to get back to write the last book. Of course, I didn't know that it was going to be the last book of the series. When I got to the conclusion, McCullough informed all of us readers that she had to stop writing the series now, or she would never be able to stop. "And this is a problem HOW?!" I thought. Gah! And don't leave angry comments - I know she has intervening circumstances. It is just that the series was so good, and she clearly likes writing about the subject matter. Sigh.
So, as I see Scalzi's series unfold, I have a small dread that he will someday say "enough" - when there is still more to see in the universe he has created. At least there will be a third book, or more, so I guess I should be happy for that.