This is a very strange manga. For one, it went on way too long. The stories became very repetitive around volume 18. By then all that needed to be said had been. A few volumes after the various confessions take place, there isn't a whole lot of meat left in the story.
In general, I feel that this mangaka's best work was his other series "Parallel" which is 4 volumes.
In specific, for reasons unknown, by volume 27 there was a drastic change in the art style, and by chapter 132 it was so bad that I couldn't force myself to keep reading. It looks much like what I've seen after an artist has had a stroke.
So, my rating of 5 is an average. The first dozen or so volumes rate and 8 or better. After vol 27, I give it a 4.