Here we are, another clash of Far-East vs West style.
Goal of the author is to show Galko is a Gyaru but common belief about this category is often misplaced.
Or, translated in western language, Galko is a "very pretty" Gyaru in appearance, but in reality she is as sensitive as any other girl and she is just trying to partially imitate her older sister.
Together with Otako and Ojou she makes the perfect trio of teenager friends which should not be taken so easily.
The discussions are mainly on those topics "which should not be told loud", so some people would consider them not appropriate for children below 14, however, in this anime there is no fan service at all (although many people will say that Galko is "sexualized character" because they just look at pictures and are not able to read / listen).
Actually it can be quite informative.