Ok, the first thing I should say, is that dogakobo's Yuru Yuri is a parody of the slice of life genre and the yuri in general.

All the characters must be taken as ridicule to the stereotypes that exist in the characters of the series of this genre, especially Akari.

The situations in this anime series are so surrealistic and ridicolous, nobody in the series take seriously the situations.

The most better developed characters, or better written, are Kyoko and Chinatsu.
Kyoko is a silly girl, her interestings are manga, anime, rum raisin, and a lot of fun, although it can be described as a selfish character, since she does whatever it takes to get her friends to do what she wants.

Next, we've Akari, the non-presence character. Her personality it's very beautiful, she is kind, considerate, innocent, a dreamer, and a good friend, but she is always overshadowed by the constant teasing of her friends, especially Kyoko.

Yui is the character without personality, has no development as such being a totally boring character, and that may be the reason why she always accedes to the whims of Kyoko, because without Kyoko, Yui is a character without identity or purpose.

Chinatsu is a very interesting character, because she looks like an innocent girl, but she isn't. She feels a pretty big attraction towards Yui, an insane attraction, since she practically wants Yui with her basest instincts. Her personality it's so variated, and this is the most interesting quality of her. It's so maniac.

The other characters are so charismatic, specially Chitose... Gosh, I love that girl.

With a lot of jokes and references to another series, this and the second season are the best in animation, because it's more a parody than a series of the genre.