If it's a private story, or a moderated story almost wholly written by one author, I'm impressed. It's safe to assume in such a scenario that the author has exercised some degree of caution about how they structure their story, even subconsciously. There's a certain kind of organisation inherent to someone's own personal project, I find, even if it might seem chaotic from the perspective of a stranger.
If it's a collaborative moderated story, I'm cautiously optimistic. A two-digit number of options, if from a range of authors, raises an issue with dilution: to find any quality content, you may have to sift through a mess of inferior writing. That said, I am initially willing to give the benefit of the doubt to a careful moderation of the story.
If it's a public story, I would need to be able to quickly identify the branch I want to read, e.g. if the introduction is high quality and I want to continue reading the owner's content. It could also be justified if there's a specific reason for such a great number of choices. Otherwise, I'm probably not interested in wasting my time clicking through them all until I find one that satisfies me as a reader.
I don't mind chapter depth as much. I'm perfectly willing to read new stories that only have 3 or 4 chapters of content in one branch. It stands to reason, then, that a greater depth, even hundreds of chapters, wouldn't disinterest me, since I have the freedom to simply stop reading if I don't want a long story.
