Totally Agree. Most important here is how they build up the atmosphere and how you get detail in every chapter about what is going on. You are not hit hard with all the facts at once. On one side I like it, on the other side I want to know more NOW, not after 2 chapters.
It is a balance that is hard to hold, but this Manga did a great job at it.
Another way good Sci-fi can be made, is when you get much information on one point, that is not crucial, but will help those who love it, understand an under-flowing story.