While the first season almost exclusively focused on the four main characters -- Akari, Kyoko, Yui, and Chinatsu -- the second season takes time to check in on the girls' classmates. A little more time is spent with the Student Council members, though they get just as much character development as the original four. That is to say, you don’t get to know much about them beyond a couple of simple character traits. Though more character development would have made Yuruyuri a much better series than it is, the series does a better job at developing its cast than similar types of series.
Much of this involves the multiple "crushes" scattered throughout the series. With the exception of Akari (who, jokingly, is invisible), nearly everyone in the cast has a crush on someone else. Sometimes the crushes are overt, with one character actively trying to kiss another, while others are bubbling just under the surface. Once again, yes, the cast is a bunch of girls, though the crushes never cross the line of being "creepy" -- at least, I never felt uncomfortable. Other viewers may have issues, but this probably isn’t the show for you in the first place.
The relationships are, for better or worse, one of the few constants in the show. Without a larger plot, it doesn’t have much else to hang its hat on other than character interactions. It’s simple, but Yuruyuri somehow manages to make it work. The series gets some help in this regard by showing just enough self-awareness that otherwise absurd plots are funny. Not everything fell into my sense of humor, but there was just enough "dumb humor" to see me through the entire season. I especially like how this sense of self-awareness carries over into the art book’s episode listings. Each synopsis is introduced by one of the characters, all of whom seem to take more time talking about themselves or commenting on the other narrations to fit in their own bit. Everything is sorted out around Episode 6, but by then, the season is nearly halfway over.
The rest of the book is as good as ever. Aside from the episode guide, the book is stuffed with character sketches of the characters, as well as pencil sketches of props/ costumes from different episodes. Also included are character artworks showing the girls in different scenarios.
Another of Yuruyuri’s consistencies is how much doesn’t change between seasons. Season 2 isn’t much better or worse than the first season. Both seasons follow the same general pattern. If you liked the first season, you’ll love the next. Otherwise, there’s nothing here that will change your mind.