A diversified cast of characters in a not-so-typical high school setting. It does a good job of making fun of the cliches of other similar high-school dramas while being able to offer something new to the genre.
It has excelling animation, good voice acting, fanservice, and a decent plot. It's a bit overrated, but still worth watching.
I recommend watching in broadcast order. If you watch in chronological order, you'll be done with the main story and will only be left with filler for the last half of the show. Plus, the ending will be episode 9, which will definitely lower your views of the show.
Its main draw, however, is its very loose setting that can be easily manipulated by the fans of the show.