These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Case in point: Near the beginning of the first episode, she accuses him off being a pervert for accidentally walking in on her while she was in the shower. When Yukinari explains that it wasn't like that, she switches from accusing him of peeping on her, to taking offense 'cuz she thought he found her unattractive. So she smashes his face in, with her knee, striking him hard enough to draw blood, and knock the guy off his feet, resulting in the back of Yukinari's head smacking the tub, knocking him unconscious!
And not only that, but she was using his shower without asking.
She Also Broke into his house while he was out to use it too...
Growing the Beard: Most people seem to agree that the second season of the anime (from episode 12) is considerably better than the first, although things actually start to improve around the seventh episode.
The Woobie: It is impossible not to feel sorry for Yukinari seeing as how the poor kid is treated like crap by his peers; has an allergic reaction which flares up if he happens to touch women, which he developed as a result of being bullied by girls his entire life. He's beaten up nearly every day by the closest thing he has to a friend, nearly all the main characters with the exception of Miharu, Koyomi, and Lisa have either used/abused him; especially Kirie. At one point, he even wonders what he's done did to deserve any of it, considering he's nice and supportive to those around him.
Woolseyism: The end of the first season has a line made more humorous in the dub where in a Hot Springs Episode, Miharu, for no good reason, gets up exclaims about a new year. Kirie, after stating it's not a new year, tells Miharu she's naked and to get back down. In the dub, Kirie actually says "Miharu, put those away."