As of V16 C85:
I really liked this series at first, but it turned into a real drag after the first few volumes. In the beginning it felt like a real story about two people learning to live together and the changes and growth in them and in their relationship as they got to be friends, dealt with other people, etc.
But then the story stopped moving, the character development died, and the relationship between Mugi and Yuu just stopped going anywhere. In volume 16, they've spent most of the last three years together, yet they got along better, communicated more, and seemed closer together at the beginning of volume 3 when they'd only known each other a few weeks.
The other thing that bothers me is that, after the first couple of volumes, the relationship between Mugi and Yuu seems to get more and more lopsided. Mugi always seems to have Yuu's interest at heart, he looks out for her, tries to be loyal to her and is a pretty good friend to her. Yuu often takes Mugi for granted, doesn't really seem to put much into the relationship, and rarely shows any interest in being loyal to him or being a real friend.
At the beginning of the series I really liked Yuu, but now I'm almost wishing Mugi would dump her and find somebody who is more interested in being a good friend and working at building a relationship with him.
Edit:
I've pretty much given up on this series. Started out with the potential to be a good story, but eventually wound up as nothing more than a sit-com: just a string of diconnected episodes with almost no plot or real story line to tie things together and keep it interesting.