Serpents is, indeed, goddamn spectacular. Usually when a book is this good people say "I want more stories about Harriman! It could be a whole series!" but uniquely, in this book, I think DRG3 gave so much weight of backstory and characterization that I feel like I know what Harriman's whole tenure as Captain of the B was like, and I don't need any more stories about him there.
It's *incredible* how many levels this book works on. It's not just a thrill ride, it's also a history and tone poem of an entire era and a hell of a surprise ending. Which, seriously, when a book starts by basically telling you up front "I'M GOING TO HAVE A HELL OF A SURPRISE ENDING" it's pretty hard to deliver on expectations that high. I'm consistently amazed by DRG3's ability to create a situation it seems impossible to live up to... and then live right the hell up to it.
A serious epic novel about the Ferengi? No way
. ...oh. Well that was good.
An epic thriller about Harriman? That guy? Really? ...oh. Actually Harriman was fantastic and that book was incredible.
A whole TOS trilogy about the Guardian of Forever? Hasn't that been done to death? ...oh. Well those were creative approaches.
Sisko leaves his family? Terrible storyline!
...oh. Actually that went somewhere completely fantastic.
The DS9 storyline is a mess after the time jump! Completely irredeemable! ...oh. Actually that's a killer new start.
I don't think any other Trek author has ever waded right into so many initially unpopular Bad Ideas and then nailed each and every one. It's almost hard to believe.