This manga was very suspenseful with a large host of interesting characters. It has a multitude of main characters, who may all begin their stories in different places or in different ways, but that have paths that come to intersect, even across generations. That's part of what makes this story so interesting, that it's being told at such a massive scale, but that it still seems to flow well and seem consistent, with characters coming up again and again in unexpected ways or places. The characters are also interesting, especially as it shows them in all sorts of circumstances as well as a at various points in their life, so it manages to develop them a great deal. It also shows a large slice of history, primarily from 1950 to about 2015, though it has events outside that as well. Within this period, it manages to tie a number of major world events into the plot, which makes the plot feel even more massive scaled. However, despite all this, there is the major issue that after that crazy ride, the payoff at the end is kind of weak. While at the beginning it starts focusing on smaller stories that slowly connect themselves to a bigger plot, which are interesting stories in their own right, as it goes on the focus on the larger plot becomes more and more important with the smaller stories ultimately never really having much of a conclusion at all. Hence, at this point it feels that all that matters are the main plot, solving the final mystery and reaching the end. How this ultimately happens though felt quite weak for the massive build up to it, and in the end, I was left somewhat dissatisfied. If there was more care given to showing how the main characters ended up and gave them some sort of meaningful conclusion, than it may have been fine. But it goes full speed towards the conclusion for quite a bit, but then just sort of sputters off when it gets there. Still, the journey there was quite an interesting ride. The art isn't a style I'm particularly fond of, and it started out a bit rough, but overall quality wise it was definitely pretty good. 

tl;dr: A manga that has a story at a tremendous scale but doesn't really have an ending that does that justice.