Season one was nice and technically impressive in places, but not particularly amazing.
Season two was worse overall but had the better episodes overall.
The movie was about half an hour too long, otherwise it was fucking great.
Azusa > Ritsu = Mugi > Ui = Mio > Yui = Jun
KyoAni are good at animating but they pick shitty source material so their shows end up kind of dull overall.
Everyone has different opinions.

Am I the only one that found the anime inferior to the manga? Great animation aside I felt the anime was inferior due to taking out all of the humor and padding the hell out of everything.

K-On! doesn't have very interesting plot or characters, but KyoAni has figured out what was the attraction point of K-On! manga: Facial expressions! That's why K-On! is so popular. K-On! is very entertaining slice of life and has provided me many smiles, laughters and tears. It may not be the best slice of life, but one of the best.