As I suspected, the series is becoming more and more serious as the artist/author gets a better handle on the characters and what she wants to do with them. She admits in notes throughout the book that she was ("is") just making it up as she went ("goes") along, which shows in certain scenes -- incongruous slapstick, breaking of the fourth wall, etc.
Oddly enough, Alice was apparently the most popular character in Japan. I felt nothing for her in the anime, and in the manga I simply can't stand her. So far, the most interesting story elements are Issei's struggle with the fact that he's a straight woman reincarnated as a straight man and the mystery of who exactly Rin used to be...