Personally I think the Marine Corps is better but I may be biased.
Orphanage is one great book. It’s probably the best military sci-fi book I’ve ever read. My definition of military sci-fi differs from publishers that’s probably why. I think of books like Orphanage as military not the ones where some vague alien officer is off doing their thing. I digress though.
I loved the boot camp part though. It really brought home the differences between Army and Marine Corps boot camps.
I’ve heard a lot of people say the book likens a lot to Starship Troopers, as I haven’t been able to make it more than 10 pages through that book, I don’t know if the correlation is spot on or not. Judging by the movie, if it’s close to the original book, then Orphanage is close to Starship Troopers but only in that bugs send rocks at Earth. The rest differs. It’s a very personal book, you almost get to the point where you care what happens to Jason Wander.
The book is incredibly strong military sci-fi. If you don’t like books that get more militaryish than a storyline that uses a military career backstory, you won’t like the book. For the rest of you, it’s a wonderful read.