I've been following this for years and just finally finished and I gotta say, I'm disappointed with the ending.
There's an interview where the manga-ka explains where the story came from and it shows at the end. Something about the editor recommending doing a story about a threesome or some such. So disappointing to hear because that's not what you get out of this story throughout most of it. The ending is also rather up in the air. It didn't come off as realistic, just as the writer not bothering.
Still, it's an enjoyable ride, especially in the beginning. It's a bit stretched out, especially with such a disappointing end. But if you think the characters will truely confront themselves with the reality and hard choices that they have to make than just start crying and or laughing now.
There's a part of this story I still remember. Where the characters discuss why they broke up, and I've always liked that because who hasn't perceived a slight just because your friend(or whatever) was busy(or some other reason), and I could relate to when the girl sees her ex having more friends or seemingly not needing her as much. There's a few points like that.
This just makes the ending that much less satisfying. It's so hard when something doesn't end well. It goes back it points a dark cloud over the experience, especially when you're working off your recollections. Still, before that happens, it's good.