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.
Ho Yay: While all three are proven to be straight or at very least straight-leaning, it's interesting that of Yuu's two closest friends in the series, he is suspected of being lovers with one (Satoshi) and the other is long believed to be gay (Bill).
Values Dissonance: This is not something you want to marathon with anyone overly obsessed with being PC and/or who forgets that the series's pretty dated by today's standards. Miki sometimes becomes very clingy and dependant on others, Yuu has occasional moments of chauvinism, and the Meiko-Natchan relationship being portrayed as it does HAS been noted to produce this reaction in some viewers.
The Woobie: Oh, so many. Specially Meiko and Ryouko.