In regards to the story so far, it's a mixed bag.
On the side of the main characters, I understand dropping more hints towards the ending plot twists. And the flashbacks throughout the game are greatly appreciated, mainly so we see a lot more of Yui than just some meek, innocent girl and more of Kirumi's personality. But at the same time, leaving them more ambiguous makes the surprises more, well, surprising. Especially for those who haven't played the original version.
As for the villains, really appreciate adding more of them and giving them more personality. Adds more to their scenes, and gives them more to do than just being eye-candy. Makes it easier to go into which ones are more interesting and unique, other than the obvious best girl (Mistress).