Animation Quality: 9
As a rating for the total series... I'd give it 8.5. The first season's character drawings are really... well... rough? kinda disappointed at first since it wasn't as good as the official poster. Thankfully things changed a lot in the 2nd season. Loved the usual KyoAni touch on using real life stuffs as the background and little details such as the cars and everything. The motions are also pretty smooth. The instruments are pretty well-drawn too.
Voice Actors: 8
The voice actors are great, but not perfect. They can deliver the expressions superbly and they also sing very well, but sometimes their voices are unstable
(especially Mugi's). I personally think that Yui and Azusa's VA are the best on this show.
Script: 8
For an anime based on 4koma manga, I think the script did a very good job. I know there's not much to adapt from a 4koma manga, so they have to make their own extension and original materials. Most of them are lovable, but some of them aren't. Several characters are having a personality change, and a lot of original jokes and little details are missing in the anime. The original materials aren't bad, though. They can give an emotional attachment very well.
Soundtrack: 10
I really like the soundtracks. It is unique and it gives a peaceful feeling. The songs are great too.
Editing: 9
Most of them are great.
Enjoyment: 10
The most important aspect of entertainment. So far, this is one of the anime that I can enjoy very much. I was always waiting forward to the release of each new episodes, and I even collected extras and anything related to K-ON!. Maybe it has no decent storyline, and whatever, but i truly enjoyed it.
Emotional Involvement: 10
This anime is the first one that attached to me very much. Man, it made me really missed my high school days, and it inspires me to do my best and enjoy my own life. I almost cried at the ending, but thankfully the extra episodes erased the sad feeling.
Overall, it's not the greatest anime and has it flaws. But for me, what really matters is the enjoyment. After all, flaw is a part of perfection.
9,1/10