I agree with Ghizguth a little, guys kinda crummy at the start, gets better after a bit in the new world. But I like that he 'grows' a bit as a person as opposed to just staying a dipsh**. Hoping for some variation in the Succubus. Like making her loyal to you alone, or a complete slut. Depending on what each player wants.
The protagonist will see a lot of character development over the course of the story, as they grow more responsible and capable, and are eventually forced to confront their past.
Regarding Valerie's corruption, you can indeed choose between keeping her loyal to you, or turning her into a full slut (similar to other succubi.)