Story: Music and cute girls. It's very hard to go wrong with that. The series itself was very light and full of fun. Although the series did have a few serious moments, the warm feeling never disappears. Nothing extraordinary or dramatic happens but that's not to be expected. What was unexpected was how humorous and enjoyable this series became. For a slice of life series, I didn't expect it to be so enticing and funny. Usually, slice of life is just a series I watch one episode of for some change of pace. K-on wasn't quite that. It was something I wanted to watch more and more of. The story moves fluidly and the pacing is nice. The ending was sweet and I would definitely watch this again.
Animation: I loved the animation. The movements were terrific and the character designs were adorable. All of it is incredibly cute which is great for me. I also appreciated the little details such as the food at teatime. It really does make a difference.
Sound: I liked about everything from the sound department. The seiyuus were terrific. All of the voices were cute and fitting without being grating or nasally. The songs were cute and fit the mood of the series. No serious or epic music but very light and catchy which fits well. The soundtrack was also great. I personally liked several pieces just as much as the songs.
Characters: The characters like the rest of this series is cute. The all have the little niche and throughout the series, you get to discover more about them. Although they may not be completely unique, they are all lovable and memorable. I would like to join this cast for tea and Mugi's cake.
Overall: A lovable and endearing series. It's light, heartwarming and has some very catchy music which is hard not to smile and sing along. I'll repeat myself. Cute girls making music and eating good food. What's not to love.