This was beautiful. It was recommended to me several times, but I didn't get an idea of what it was, so it took a while to get around to it. I'll try to do better:

On its face, it's a space western - a ragtag crew on a lonely and perilous journey to do a thing. And it does that space western well.

But it also demonstrates Heinlein's assertion, that the best science fiction only looks like a "gadget story" - in this case, space hard rock miners tunneling through extradimensional space - but is actually a "human interest story" about the people involved. And it does that people story well, with a constellation of deep, meaningful, and evolving relationships.

But it also also puts me in mind of the old Jargon File note on hackers holding an inclusive view of personhood. Half of the people in the book are not human, and Chambers does a brilliant job of demonstrating that these nonhumans share in real personhood while (mostly) avoiding the Star Trek "humans in funny masks" version of aliens: half a dozen non-human characters are offered as fully distinct physical/cultural/psychological models of personhood, and the human interest pillars of the books demonstrates how intentionally navigating these distinctions while respecting the personhood of all involved is what makes for a successful civilization.