Although I can see most people saying this story is underrated, it's not. People just don't talk about it that much. Also, I am up-to-date with the manga, so I can say this much:

Story: It's not that bad, but not entirely the best. But one thing about it is that it's not at all predictable, unlike other manga series. Okay, maybe sometimes it is, but it's still good enough for me. One more thing about the story is that it somehow related astronomy and used their own words for it.

Art: It doesn't really suit my taste. It's a simple style though, which I can easily understand. I can figure out how the fight/battle scenes are supposed to look like, which is okay. I've only seen a few colored parts in this manga, but it's simple and it doesn't hurt your eyes, so it's okay.

Characters: The characters in this series are likable enough. There are times when I slightly find some to be annoying, but it doesn't make a huge difference. The characters slightly relate to some people in real life, so I think it's fine. You can easily tell the characters apart, which is a good thing too. All their abilities are explained well and the way they think in this series is good.

Enjoyment: Personally, I'm really enjoying the manga series. It gives the right amount of twists and turns, not in every chapter though. Eh, it's not especially better than other manga series that I'm currently reading, but it's not bad at all. Although to be honest, I don't think those who like a lot of action would like this. It stays loyal to its "sci-fi" genre. The characters, plot, and how things work in this manga are well thought of, so it would be hard to say you don't understand what happened.
So, would I recommend this? It would depend on the person, but I think it's worth a shot.