100% complete on hard mode in 48 hours (I tend to play games slowly, probably could be done in 30 hours or less).

Pros:
Music - Not as good as most Atelier games, but still pretty good. Has a different sound compared to other Gust games. Music transitions during boss battles.

Unusual enemy design - particularly some of the bosses.

Okay:
Main story - Pretty decent, though is mostly predictable past the prologue with a little twist towards the end of the game.

Area design - Some areas have some nice visuals, but the school doesn't feel fully realized and the other areas never feel thematically connected.

Battle system - All characters take turns based on a timeline, with the bizarre caveat that enemies are shown on their own timeline. This makes it difficult to tell the exact order at a glance and instead you always need to check the numbers underneath the portraits. The main unique addition here is "Ether", which controls passive recovery, timeline speedup, defending, and Overdrive, the ability to use multiple attacks in one turn. Unfortunately, the main way of gathering Ether is to choose the Ether Charge option when a character's turn comes up. This option recovers MP and Ether while the character is still moving on the timeline. However, putting one or more characters on what is basically standby when you only have access three characters hurts. Enemies are also easy enough that there is no need to push the system to the max. You could probably even get away without using the move-powerup tools called in-game as Fragments. Battling regular enemies is only for gathering materials.

Cons:
The scope of this game is tiny, with a budget that is even smaller. (I am talking about something that is probably even smaller than, say, Soul Hackers 2.) It is basically at, or even smaller than, what you could expect from an indie game. This amounts to the school and four other places being the only playable areas. The 2D backgrounds in the side story scenes appear to be photos that are lightly edited and run through a filter. The number of different enemies is very small, with each having four variables with texture and slight model changes. Most bosses are fought twice.

Side stories - Most characters have something of an arc in their side stories, but the small scope makes them all pretty shallow. Most have an arc that kind of feels at odds with how they are portrayed in main story scenes. One character is part of the cooking club, but the concluding event in her arc involves a rap battle. If there was space for more character events it could have worked as representing different aspects of a character, but the game just does not have the time to waste on that.

Crafting - Very simple. Item A + Item B + Item C = Item D. No interesting systems like in Atelier.

Graphic issues - Ambient occlusion seems to be partially broken, with leg-shaped shadows hanging off the sides of characters. Godrays also seem to not scale to resolution and show pixelation in some shots. Depth of field works, but breaks in certain cases and cannot be fully turned off.

Fanservice - Pool scenes, bath scenes, changing room scenes, showering scenes, wet semi-transparent shirt scenes, and also, onsen scenes (though this one does not show much of anything). There really is not any justification for these scenes. (Ar tonelico had better reasoning for the fanservice, but even that was pretty unnecessary.)