The final volume: Death's End, is by far the least coherent story. Due to hopping in between eras, the story feels to fragmented, even if most of it is through the eyes of the main protagonist.

As with 'The dark forest', this character was not really relatable either. No biggie though. For me, the main character was humanity as a whole.

One main plot element builds on the conclusion of Death's End: how does humanity implement the 'Dark Forest' idea? That could have been more interesting if there had been fewer eras, but all in all, the overall picture was compelling.

The final part of the story felt a bit rushed. Suddenly, humanity was wiped out by a third party. The story ends a bit abruptly . The few surviving humans are saved by a Deus Ex Machina and are released in a reborn universe at the end. All in about 100 pages. It felt anticlimactic to me.

The science in this story became more trippy as the story progressed. That was fun. Also, the evolution of humanity in the different eras was interesting. It would have been fun to explore those societies further, but I understand that this would have made the book even bigger and (for some) more inaccessible.