It's a really cool story. I enjoyed the plot and the branching, and I thought the protagonist was a fine character. For some reason that I cannot quite identify, I feel as though this story ought to be taking place some time in the 80s. I picture all the characters running around with big 80s hair. (Maybe it does take place in the 80s and I've forgotten the part where it says so?)
Anyway. It's a vampire story, and it's confidently told. Vampires have been done to death (and undeath) these days, it seems, and it almost becomes a game of mix-and-match tropes when a new vampire story shows up. There are no apologies here, and I found the tropes nicely handled. Ralon and Matthias are recognisable types, as are their approaches to vampirism; yet they don't seem to quite fall into stereotypes. Indeed, I found the characterisation of the various NPCs pretty strong, over all.
Unfortunately, I do notice a few holes in the progression of the story. There are places where the pieces don't join up as well as they should: references to acts or observations that had never been made, characters disappearing or reappearing because the branches that arrived at the particular section differed in who was or was not there. There is also some inconsistency with tenses. It's a cool story, confidently told, but in need of an editor.
As far as story structure goes, it's a very classic CYOA. You follow branches through the story, and the story follows roughly the same outline. Choices are recognised only in the sense of which branch brought you where -- I don't notice any state tracking being employed. It's fairly old-school CYOA, the sort you could follow in print. I doubt it'll win Best Use Of Medium any time soon. Still, for what it is, it manages quite well.
Pastrami on rye, with cheese. And black coffee. Technically it's breakfast, since it's 5am, but you've been up all night....