I just beat this, at close to 100%. (Apparently I'm missing one ring, one crafting material, and two codex entries.)
The combat system is fantastic. Switching partymembers freely is the next best thing to having all of them out at once, and creates some interesting tactical considerations of itself. Switching equipment midfight is really cool, enough that I wish there was a recharge mechanic for that rather than making it once-per-battle. Free enemy analysis, rules reference, and viewable nonrandomized initiative order, are all huge quality-of-life benefits. That last one also makes it clear exactly how much the Agility stat is worth, which it turns out is a lot.
Characters are split. Ezekiel's pretty cool, Umbra's generally a standout, Bolinda's hilarious and I wish the ambiguity about whether her Gang was actually real didn't collapse toward the negative after her fantastic bossfight, Jim Jam was entertaining, Boderick was great, and Sita started as oblivious and separately a bully, but grew on me. Rick was pretty consistently awful, but he had some interesting interactions with Ezekiel, and he kind-of-sort-of grew up a little by the end, maybe, I guess. Brave Wind had potential, but his plotline is almost entirely about killing innocent creatures who talk, and his last line of dialogue is accepting with good grace Umbra being pointlessly mean to him. He'd have been more interesting if he had a bad example to play off of, which Rick could easily have provided. Emith's Zatanna schtick (using phenomenal cosmic powers to fake stage magic) could have said something very interesting about him, but the story never really delved into the requisite worldbuilding for that, and he doesn't really have anything else going on. He's also the only character who plays into most of the damage type system, and that feels like a missed opportunity. Finally, Kyme himself... cares a lot less about having killed Death, or the Excrucian-grade kleptomancy that apparently exists, for someone who moved to a completely different town because his... wife? Girlfriend? Completely blank-slate plot device? - died, than such a person really should. His love of walks and his party-defending combat style were interesting enough, but not enough to make up for being an insensitive skirt-chaser at best, and an adulterer at worst.
A number of fights feel morally reprehensible. Lamia wasn't actually eating children by the time you fight her, first Rat Man encounter is one you can run away from and he isn't obviously breaking in to Macy's house or stealing anything, it very definitely should have been possible to progress the Ruined Keep sidequest without killing the Knight, or at least given some indication that fighting was the Knight's choice rather than the party's. Arana's Den felt kinda bad-faith, given that I literally couldn't avoid fighting and had tried. Fairies did not appear to deserve death, especially for the sake of a single fake resurrection potion, Brave Wind had absolutely no right to murder his way through the beehive, and ending the Illusionist's tea party before at least partaking of crumpets was just rude. He seemed fairly harmless, regardless of how incredibly long his bossfight took.
I loathed the ending. The bad guy's philosophy has huge, glowing weakpoints in the form of every victim whose lives he categorically did not improve, which seems to include the sailors whose boat he stole, the woman whose voice he stole, the Harps whose goddess's favor he stole, the children whose capacity for laughter he stole, and of course the party, whose combat skills he never returns. And because the PCs never properly bring this up, once the Grand Thief has run away, he's won the argument: Kyme goes and seduces Serene, who is married to someone else.
(Serene isn't even an interesting character! Just a jerk too dishonorable to return to her husband or properly divorce him for leaving! Sita and Bolinda are far more entertaining, and if it's just a matter of attraction, Morning Star is obviously hotter!)
It's intensely frustrating. A lot like Jimmy and the Pulsating Mass that way, with which it shares similar strengths and weaknesses.