The good news: Very very well written and researched. There is 3 times more content per page here than you will find in 90% of your average sf novels.
The not so good news: The story line is strictly rutine. Seen before many times.
The not at all good news: The characters are boring. This is IMHO Stirling's chief weakness as a writer. They have max 3 qualities each. It is a problem for the reader (or at for least this reader) when s/he at the end of a book does not care if the good guys kill the bad guys or the other way round. OK, there are silver linings. This is not a good guys versus bad guys story. It is the in mafia versus the out mafia. This is an improvement on Star Wars and Stirling must be thanked. And the heroine is not Cinderella. Instead the hero is Cinderfella, in fact very much so. Nice.
Another matter: Alternative history novels usually start with the beginning and work their from there (as in Stirling's Nantuckett trilogy). Here the story starts 60 years after. This is new and not unwellcome.
If you are a Stirling fan, buy the hard cover.
If you are interested in ecology and green stuff, buy the hard cover.
If you are a normal sf fan, wait for the paperback.