I was very happy with this first episode. All of the seiyuu did a fantastic job (what a wonderful surprise to find Saori Hayami as the library sempai!) with their respective characters, but I was quite impressed with Ayahi Takagaki. I had some reservations about her pulling off Sumi, but she has more than proven she can handle the role.
Also, I love the bgm and op/ed. Wonderful music all around,