I read the first two books and loved them. So creative, interesting and suspenseful. They kept me flying through the pages and I'm not a science-fiction fan at all.
Then this monstrosity! I got it when it first came out and struggled to read it. So many simultaneous stories, it was impossible to keep them all straight or even remain interested in them all and the connections between them were faint and unexplained. Many of them in the end seemed rather irrelevant. It took me 7 years and about as many tries to finally finish it and that was only thanks to audiobook and the motivation to finish it before the Netflix series comes out.
Simply and sadly said, this book is terrible and such a disappointing end.
My suggestion, read the first two and watch the third or make up your own conclusion. It will be better than Liu Cixin's.