Overall it was an interesting game and idea. It's not personally my favorite style but I can tell a fair amount of thought and work into it. Moving quickly past the obvious you're likely already aware of: more art options, animation potential, longer story.
The girl's voice was nice, and she was surprisingly convincing. I don't fully agree with the first commentor, but a few things I'd suggest is to level out her overall volume. She whispers the story in comparison, and obviously I'm not implying she should talk normally at the same volume she ?screams? during the scenes. (some dialogues are abnormally quieter, at least that's how I felt)
This would be a bit complicated, but it would add quite a bit. I noticed that no matter HOW you get to an option, it always has the same story line. The only one that really bothered me though was for Ending 1. After you choose to "let her suck you off" or "face fuck her", "keep going" 's dialogue is completely out of place for the "let her suck you off" option from before. More specifically, you calmly allowed her to do her thing, and then you're raping her mouth essentially by continuing when it would fit more logically to at the very least have a segment of transition into that option since it was fem-dom and chill before. Some of the others such as spank could be elaborated upon as having an effect in the following scene.
I'm sure for others who find this style more appealing it would be worth pursuing.