The second half of OVA episode 1 may qualify as well. It is a nice subversion of the usual My-Beloved-is-So-Flawed cliche, as Sachiko sees right through her cousins' attempts to denigrate Yumi and is not shy about her disgust.
Ensemble Darkhorse: Sei, the original Rosa Gigantea, struck as one of the most popular characters at first for being the most notable lesbian of the show. In latest seasons, Noriko seems to have gained plenty of popularity. The White Rose Family can be considered the Ensemble Dark Horse Family as it is the most popular family in the fandom despite getting considerable less screen time than the red and even the yellow one,
Family-Unfriendly Aesop: The message of Mifuyu's story appears to be: "Accept that other people are more special than you."
The message of Sei's backstory seems to be: "Societal obligations will sometimes keep you from someone you love. Learn to accept it."
And both are messages that, while regrettable, are still prevalent in Japanese cultural mores.
Memetic Mutation: This series is responsible for the word "Gokigenyo" being known among anime fans. And of course, thanks to this work and Strawberry Panic!, "onee-sama" has a very heavy Les Yay subtext.
The first scene, in which Sachiko fixes Yumi's scarf, is often referenced and parodied, especially when hinting at romantic involvement between girls.
Narm: In one episode, Yumi and Sachiko run at each other to hug in a emotional moment... while Yumi is wearing a panda suit.
Seinfeld Is Unfunny: The series has been copied and especially parodied mercilessly, to the point where viewers suspect it to be a parody itself. Admittedly, the romantic entanglements between the girls of the depicted all-girl school do get rather fluffy and melodramatic at times, but it mostly kept in check by the tight storytelling and outstanding voice-acting in the anime.
Snark Bait: This is a shoujo-series with a very idealized view of homoerotic relationships and an overabundance of The Beautiful Elite, what do you want?
Touko seems to attract a lot of hate from the fandom
Fans also tend to be exasperated by Yoshino's numerous bitchy outbursts toward Rei. Sure, they usually make up sweetly, but fans feel that meek and mild Rei really doesn't deserve all the bile Yoshino piles upon her.
Wangst: Largely averted, although Touko's self-torture about being adopted comes dangerously close at times.
What an Idiot: Shouko goes to the tea party held by Yumi and Yoshino, hoping to get noticed and get into the Yamayurikai... but instead of focusing on one girl and wooing her, she says either one of them is fine, thus spoiling her chance to be liked.