I’m generally happy to accept fiction about science as science fiction.

Old Man’s War is about old people getting new bodies in exchange for military service in war against aliens. I thought that it would either be good, or be a guilty please, but I found it very boring. John Scalzi is popular though, and generally considered a very accessible author. If you were hoping I was going to roast it then sorry, I mostly just forgot it.

Don’t read it, it’s not interestingly bad, and at least A Princess of Mars is historically important. The only reason I could think of you wanting to read it is if you read Starship Trooper and The Forever War first, and then wanted to read Old Man’s War because they get treated as the trinity of big SF military novels. But those other two books are important. Old Man’s War was probably voted #1 in that poll because it was something that people who wanted a book that reminded them of the books they liked growing up could rally around.

Really, if you read The Forever War and then want to read something shockingly terrible, read the sequel, Forever Free. The second half of that book is indefensible. It’s not offensive or anything, it just reads like a story idea that was submitted by an author after they forgot to take their medication, and then the publisher rubber stamped it because it was going to be a sequel to a classic so they knew it would sell, and later the author just rode with it because they’d already agreed to the book. It’s short and I don’t regret reading it.