Not as revolutionary as people said it was but it's pretty good. My favorite part of the game is the narrative design, which, to sum it up, is akin to filling out a jigsaw puzzle. It almost makes me feel angry everytime I see someone call this a visual novel seeing that a lot of effort went into that part of the design (there wouldn't be anything wrong if it was really a VN, but with that criteria you might as well call monkey island a VN at this point).

The other parts of the game can be a hit-or-miss, for instance, the visuals look gorgeous but at times it can look wrong, specially on the less chaotic sceneries. The character art looks gorgeous, my favorite being the sprites during the events (they have those Akihiko Yoshida-ish eyes that I love).
The combat is fun but there are a few improvements to be made: how the turn of each pilot is managed doesn't feel right and it doesn't help that the UI is a mess. It also has a tendency of interrupting you while you're choosing an option during the most complex waves.
I liked the plot for the most part, some of the revelations left me making loud monkey sounds, and others were pretty predictable, specially towards the end.

Overall it's pretty good, I recommend this especially if you like Zero Escape/Uchikoshi types of stories.