The custom assets (battlers, chapter splash screens etc.), and general presentation are quite good. The writing is pretty good overall, though I think there's not a lot of tonal consistency or coherence - and if that's by design, it's probably more jarring than intended.
I know it's not a "serious" game given the whole anime intro song and whatnot but at the same time there's some deep / introspective dialog which would probably land better if the game had a more cohesive voice.
Gameplay-wise, there were a ton of features that I almost liked but almost every aspect of the combat in particular felt like an opportunity to do better.
The UI of the combo system took a while to get used to. I wish the Help box would just display whichever combo effect you were going to get (if any) as it was just information overload seeing all of the descriptions for the abilities themselves, plus having to wait for the combo state icons to flash back so you could remember which letter you'd already inflicted. I am aware part of the battle system is dealing with "tank" enemies, but at the same time that's super annoying because when you go to set up a combo on a solo target only to have 3 tanks drop out and disrupt your plan it's a big feel-bad. I think if you were to refine this combo system further, I'd consider making the A/B/C thing a global effect not a target-specific state, so at least you can't get randomly screwed by tank adds.
I'm unsure if Seal doesn't work properly, or if part of the intended design was to not lock out all AoEs but rather just specific ones. Either way, I found myself under-using Seal because I could never say for certain if it was working.
Enemies feel like bags of HP. Most fights drag on after a particular phase is "solved", but because there's no way to determine how many phases an enemy has you can't determine whether you need to conserve resources or not. I found myself getting frustrated very early not by the difficulty itself, but by how much of the difficulty is just due to the fact that the character abilities and interactions demand planning while the boss design precludes planning.
If you get the boss' HP bar down to 33% at the wrong time (low on resources) you're hosed. Whereas knowing that it's a 33% tipping point you could sandbag a bit and regain MP/Focus.
I think non-boss fights being skippable is somewhat at odds with the fact that grinding is encouraged and possibly even baked into the intended difficulty curve.
There are a ton of mechanics, and some of them are absolutely neat individually, but they don't all play nice together. Ultimately it felt like a choice between farming to power through, or bashing my head against every boss fight, and either of those was too much of a slog to commit to.