Odd that I'm the one to make this thread considering I never planned to watch this series in the first place.
Copy/pasted from MAL cause I'm a lazy bastard.
K-On!'s story revolves around four Japanese high school girls who join their school's Light Music Club to try to save it from being disbanded. However, they are the only members of the club, and the last recruit, Hirasawa Yui, has no experience in playing instruments or reading sheet music.
I've only seen the first episode and I'm enjoying it. Mio is pretty much my contender for best character of this season. Also the ED is epic.
K-On! ED: http://www.youtube.com/watch?v=GUKwH81csts