This series has a lot of potential, but unfortunately it didn't really come together.
First, its atmosphere is really unique, changing from a carefree tone to a serious one out of expectation, especially in the beginning. However, I don't think this kind of story telling gives the viewer enough time to digest everything. I don't mean the story itself is confusing, but how the plot is executed compromises many scenes that could have been the defining moments. As a result, the story seemed really trivial. I don't think it's the fault of the content of the story, but how the story is told.
Then the characters...the main characters are very likable in my opinion. I can see why the anime glass mask is among one of the recommendations. The heroine and the hero in both series are very alike, and their relationship is similar. I won't spoil too much, but the heroine in nijuu mensou no musume doesn't care for love.
Even now, I have a hard time deciding whether I liked this series or not. I was glued to the screen the whole time while watching, but I still think the show failed in its execution. It is entertaining enough, and usually I don't mind innovative execution as long as it doesn't compromise the story. In this case, I was disappointed. I haven't read the manga so I don't know how closely it follows the manga. The series has basically two nicely paced story arcs, but the themes are all over the place. In the end, I honestly don't even know what it's trying to say. That's another major disappointment.
So overall, I don't think the series is organized well. I really do think it has so much potentials though. It's just so disappointing when I got to the end. I didn't like the ending either, but that's just my personal taste in closures.