No, just no. No more Scalzi.
This book can be entirely summarized as: old guy signs up for the military because they'll give him a young body, and he fights several uninteresting battles.
That's it. Don't look for cool tech, cool concepts (there was almost a cool concept with actually travelling to different universes, but Scalzi didn't run with it or bring it to its logical conclusion with finding the dead wife alive), or cool anything.
Some issues with the book:
Conclusion: No more Scalzi unless I get some really strong recommendations from people who know what I thought of this book. I suppose Scalzi has progressed as an author, actually, since I rated Redshirts higher, but I'm going to need some strong recommendations before I read him again.
At least The Forever War by Joe Haldeman was written in serviceable prose even if it was emotionally aloof.