While I can't be as harsh as
@Cyro11 (page 2), I do feel like this manga isn't as splendid as people above me are saying.
The author definitely tends to pull plot out of her ass from time to time. More than once did I go, "hold on, where does that come from ???". Not to mention this tendency of overusing the classic "I was bad guy, but now im good guy" trope... it gets especially annoying nearing the end.
Also, has anyone talked about those flashbacks? So many of them in the latter part of the story... These completely blow the pacing apart, especially when they interrupt the action only to tell you stuff you already know. It's as if the author wants to tell us, "see that hint I gave you earlier??? Here's what it means, see?? It means that, alright? Is it clear enough???". I feel like the story does not speak for itself most of the time...
To conclude, while the concept is, in my opinion, really interesting, and the beginning, very well done... unfortunately, the story tends to degrade more and more nearing the end. As if it was rushed, as if the author needed to come up with something, quick, too quick. I feel Inuyasha suffered from the same fate, good start but poor second half.
PS,
the ending was absolutely godawful: why did Kasane kiss rat guy? why did she wanted Neena's mom to see Neena's last words? How did Neena's mom learn about permanent exchange and why did she do it... It makes no sense to me.