An original story using characters by Huke that takes BRS into psychological territory that I wish the anime took better advantage of ... is how I would say this manga is. The overall setting can feel a bit trite, as there are plenty of stories out there about afterlife stuff and between-heaven-and-hell environments. But, that doesn't diminish this hat in the ring in any way.
At first, the chapters feel like they're pretty one-off bits, with new chapters having new villains and new mental prisons to explore. These get tied together into a single narrative as the nature of the world is revealed, as well as the final boss, that kind of storytelling style. It all wraps up fairly nicely and pretty satisfying, with few loose ends to bother poking at.
The art is a bit strange. Facial expressions strongly remind me of Muhyo and Roji. Black Rock Shooter's body proportions are strange in some instances, appearing like a long, flat noodle. I suppose that is a way to convey movement? Either way, the environment art is an interesting way to display a broken world, and there are lots of messy swatches to show fragmented mental states. Overall, it's pretty solid.
It's a different story from the other BRS alternatives out there, but I would give this a pretty high score as a narrative. Compared to the anime, this is better explained and finished.