The Dark Forest

This is one of the greatest hard sci-fi series I've ever read, and I've not even read the final part of the trilogy.
The main problem of the previous part of the book was the characterization - this part solved it, and how! The characters are not paper cutouts, for once, and Cixin just loves to string along the reader on tangents that are absolutely relevant to the plot - you just realize it later.
And the way seemingly disparate elements like eleven-dimensional particles and cosmic sociology are harmonically merged is nothing short of mind-blowing. The sci-fi part of the book is not at all difficult to grasp, but it still manages to hold your attention all the same, since it takes every trope about sci-fi and first contact there is - and throws it out of the window.
To summarize, I would recommend this series to everyone who has the slightest bit of interest in how futuristic science will look like - this book is sheer, unadulterated delight.