Warning, spoilers for the previous novel in the saga!

Wow, this was a dark one.
It All looks like a 400-years-long, galactic chess game: on one side, the trisolarian fleet, that will reach earth in 400 years. On the opposite site, earth. Aware of the incoming enemy fleet, unable to make any scientific progress. Moreover, every single word said or written on earth Is intercepted by the trisolarians. No secrets are possibile.
An apparently unwinnable situation, and yet there's something hiding in the axioms of cosmic sociology that seem to scare the trisolarians...
That's a great plot right there, in case you had any doubts. Hiding an unexpected, dark answer to Fermi paradox. Alas, there's also the same issues that plagued "the three bodies": unappealing writing style and very weak characters. Still, the plot alone is enough to justify the read.