Thank you so much for this thoughtful and detailed feedback! I think I know what you mean about Alan's face. There's a few times, especially when he's stripping but before he's fully naked, that his mouth and eyes look unnatural.
Regarding story; I know what you mean. Part of what makes a VN so hot is the interplay between story and image. You develop an investment in the characters and then when they get busy it's even more sexy. That said, I'm not sure how much story this particular game will have. I'm not saying no, I'm just not sure yet. Part of why I chose to do this as my first game was because it doesn't really have a story and I felt it would allow me to better learn the software (Ren'Py/Daz) without getting too hung up on other stuff.
I definitely plan on doing more story-driven projects in future. I also plan on using some of these characters in other stories where their roles will have more of an impact on the plot. And that said, I'm still not saying no to adding story details in this project, I'm just not sure yet.
Again, thanks so much for the feedback :D