Reminds me of Eternal Sabbath. It's wonderfully dark and thought-provoking and how can you resist all that awesome kick-ass battle scenes and the sci-fi-ness?? Um, I do NOT find it lame (although yes, there are some concepts of science and all that which I don't understand, but still, it's not BORING) and I think it is VERY realistic. Especially the battle scenes. And the characters... my god, they're in-depth.
The only things I have against it are the unnecessary sex scenes that pop up every once in the a while (but whatever, this is a seinen manga and the intended audience are like middle-aged guys) and that sometimes, the manga gets confusing. There's lots of characters and new ones are always appearing out of thin air, while the old ones hang in the background until they reappear to surprise you at random intervals. It's kinda hard to keep track of who is exactly who. And the plot gets... weird sometimes. Like there are moments when I'm like, "What was the whole point of focusing on what's-her-face for 5 chapters and then killing her off?" etc, etc.
The art... I love it, surprisingly since I'm always picky about it. It's not flat-out gorgeous or perfect, but I like how realistic it is (more or less) and it's definitely not bad enough to disrupt the whole thing.
Did I stress how realistic it seems? It's not just the plot, but even the dialogues and most importantly, the relationships between the characters and the portrayals of... emotions. Very touching at times. I love how even the minor characters have their own limelight.
It's moderately-paced, although a bit slow in the beginning. But believe me, it's worth reading! I have not been able to put it down since I picked it up yesterday. And the philosophy bits in it and the stuff about religion... just really, really intriguing.