I want to start saying that this manga may not be the easiest reading; the plot is like a puzzle, at first you get to see the big picture, but without getting into the details, you won't reach the end result. I must say that this may be my favorite part about the series, each little detail is relevant either for the main plot or to get some character development and that enriches the story more and more every time you read. There's actually no time to get bored because everything is in constant movement.
The characters development here it's delightful as no one ends the same way they started, they go back and forth in their own individual worlds. The premise here is that there's not one only way to act, but actually a wide range of options where everyone can go at their own pace, and that makes possible for us readers to experience first hand the emotions/thinking that made a character the way they're at the moment or why they decided to change in some point.
Finally, the art. The main points are it's beautiful settings, a great amount of details, and a unique way of expressing emotions. In this last point I want to emphasize, because Mochizuki Jun is not only great with words (like those white/black pages that made me cry with dialogue solely), but the way she can make a few pages or even with just a single smile to overflow with emotion makes this manga a master piece.
Hope this would help you if you're still not sure about reading it, but give it a try.
