I really waffled on the number of stars to give this, since I'm trying to rate this not just as a standalone book (which deserves 4 stars), but as the stand-in for a full series review (which is much closer to a 3). I'm ... half way? through the series? as I write this, and I'm invested enough that I plan to finish. A few of the plots feel a bit sloppy (e.g. a character introduced part-way through a book as an antagonist, given part of a reconciliation arc, and then killed off later in the same book), but with a series this long, not every book is going to hit right for every reader.

Things I like:
This series is LGBTQIA+- and poly-friendly, despite some outdated language choices (to be fair, the first book is from 2006, and the author seems straight to me; it's all pretty forgivable). At least one primary character is bisexual, and several are poly. As we do in the real world, they have queer and poly communities around them, as well.
The metaphysics seem well-thought-out.
The overarching plot holds together well so far.

Things I dislike, or that would make me unlikely to recommend it:
There's rape. At first it's merely alluded to, as an important part of one character's backstory, but then it happens "on camera," as it were, in more than one book.
Some of the sympathetic male characters are pushy/controlling in ways that I find off-putting.
One of the primary narrators is awfully whiny, even after a lot of time spent in "character growth" arcs, and I don't find her sympathetic at all. Her romantic plot is also less-than-convincing, though there are moments about learning to live with a partner that feel true to life.

The audiobook narration is generally fantastic, though it pains me when, several books in, the narrator forgets how to pronounce "youkai." There are a couple of other words that are inconsistent between books, as well, but this is a common problem for long series.