The series opens with the three main characters starting their first day in high school. The main characters consist of three girls: Yui Ichii, Yuzuko Nonohara, and Yukari Hinata. It appears the focus of the series is supposed to be on these girls joining the school's Data Processing Club, but you only see the club room for one scene near the end of the first episode. While the girls spend time in the club room, they donít decide to officially join the club at the end of the episode. For most of that first episode, the audience is essentially seeing vignettes of the girls going through their day, with no real evidence of an overarching story.
The series, as well as the main characters, definitely fall into the "moe" vein; in fact, the girls fall into very particular "moe" tropes. Yui is the serious girl, and serves as the "straight man" of the group. Yuzuko is the one who is most likely to be hyperactive and act rather annoying; she also has the stray bit of hair on top that tends to move around on its own in weird ways. Yukari is the sleepy girl who tends to mimic Yuzuko's antics. To be honest, with the way Yuzuko and Yukari keep picking on Yui, I really don't understand how she can be friends with them.
When I watched the first episode, the focus was definitely more on how "cute" the girls are than on any real story or plot. In my opinion, not much of anything really happens in the first episode, and I found myself becoming bored and wanting to fall asleep. Hopefully, the first episode is an anomaly and that there will be more of an attempt to try to tell a story in future episodes. However, I'm not so curious that I'll rush out to watch future episodes in order to find out.
If you're looking for an anime with substance and some kind of a noticeable plot, then Yuyushiki is probably not for you. If you enjoy watching anime that features cute-looking characters and don't care much about plot or story, then Yuyushiki will probably be right up your alley.
Content-wise, I didn't see much that would be terribly objectionable for younger viewers. Personally, I would recommend Yuyushiki to anime viewers who are 13 or 14 years of age and older.