They don't appear to be making any attempt to have the narration use inflections for different characters. This is probably fine for nonfiction books, but for fiction books, it can make it really hard to follow when a narrator does this, at least for me.
I understand this sentiment. I've been an audible subscriber since 2002 and have listened to hundreds of audiobooks, mostly fiction. The ability of the narrator to provide distinct, interesting voices for each character figures prominently into my enjoyment of a book. This technology sounds fantastic, and will likely enable pleasant narration of texts that would otherwise never have it, but I don't think it's likely to replace professional narrators for a large number of cases.
They don't appear to be making any attempt to have the narration use inflections for different characters. This is probably fine for nonfiction books, but for fiction books, it can make it really hard to follow when a narrator does this, at least for me.