I'd heard that the story was damn near incomprehensible, and whoever wrote that was right. It jumps all over the place, and it’s pretty hard to follow. It's not that the writing is difficult to understand, the story just literally doesn't make sense. If you consider it to be more of a collection of random short stories set in the same universe, it seems to make it more understandable. Since it was his first work, though, I'll cut him some slack.
The art isn't Shirow's best, and the detailed backgrounds you come to expect from him are nowhere to be found. There was even one panel where a guy was missing an eye for no apparent reason.
The characters never really get a back-story, though I'm assuming that they're supposed to be like gods almost. It's really hard to tell.
Overall, I had fun with this piece, but I can't really recommend it.