I thoroughly enjoyed this series. Many of the characters (although not all) are developed throughout the series. I personally believe it was carried out nearly flawlessly, demonstrating around half of the group's depth of character. Sadly, with a 13 episode series, going through each person would take much too long.
In terms of storyline, it was truly an inspiring series that drove me to work harder towards my goals. At the end of their first performance, I quickly understood that this series would grow into something much deeper than a children's anime about becoming famous. This series kept the light-heartedness desired in school-based anime while not wavering to add more elements to the story to develop into something truly enjoyable. A short and well-done series overall.