I though this ending was very nice and fitted the show perfectly. They left enough questions open to keep us wanting more, and everything points to the studio wanting to do more as well. The show looked visually very appealing, animation looked good too, so unless this show REALLY bombs (doubtful, as the manga is doing quite well), I see no reason for a second season to come eventually.
9/10. Wanko is (as far as I can tell) the only element that prevents me from giving this show a perfect score. She annoyed me far too much and only showed her good side way too little times, which hindered my enjoyment, especially in episode 7 and the previous one.