Although I don't make reviews of movies (only read and maybe comment with friends), Shinkai's movies just force me to. My first comment was of, in my opinion is this director's best work to this day, 5 cm per second, and so this is going to be my second comment.
With that long introduction said, I must say this movie surprised me, with a scenery a OST worthy of the highest regards (like Shinkai has us used to) and a character development spot on. Not the deepest analysis in each character (he couldn't do that in 45 min) but deep enough for the audience to understand them and know what they are going through which is the whole point of the movie. All this wrapped up with a spectacular climax. Although you feel the climax coming, you don't expect a climax like this, with that much energy, sentiment, and art, all in 2 min long.
To finish, a little opinion on Shinkai, I have seen all his movies and I sense that him, with this movie, just realized what are his strong points: not huge movies with 8 characters and lots of themes (a ground where Miyasaki flourishes) but little situations where few characters stand for being truly humane and how they confront problems that ,at that time, mean the world to them and shape them for the future. He's a director that likes to test new grounds (part coming from being a young) but he's also getting reaching his full potential. That's why "Voices from a distant star", "5 cm per second" and this movie are his best work to date and "Voices from deep below" and "place promised" being his not so good movies (although I liked them).