Humor might miss the mark. At least, I didn't find much of it. Though, I wasn't looking for that when I played that game a few years back. This game is undoubtedly just as dark as it though. It's just the humor here is really what's nerfing some of it compared to the other game. Which is great in it's own way.
To be honest, having played both (I didn't realize I had played it before until I Googled it), I kind of like this one vs. the other one. While the other one had a great story in its own right, it didn't flow as well due to the choices on where to go. Sinful Vampire, however, has a seamless story kind of feel, and the humor does kind of add to you as well (though that is my opinion; maybe I enjoy the dark humor and banter because that's just who I am LOL).
I will say a lot of my opinion is speculative since Sinful Vampire doesn't seem to be anywhere near done yet (but it's hard to say how much longer the story will last since the only one who knows would be the dev). The one thing I will say is I do enjoy these kinds of AVNs. Ones where you are playing a "powerful MC." Stuff like this, Nephalim, Sicario, as well as quite a few others. It's also nice that there are more good vampire MC games out there since there don't seem to be a whole lot of good ones out there (that I have seen).
My one complaint, though, would be when you find out that you are a vampire; her whole "swan dive" thing was kind of cringe, but it seems to have gotten better since then.