I love this anime. It was the first one I ever watched, and it will always hold a special place in my heart.
That being said, after returing to this and watching a few episodes again I can say, reluctantly, that it's a little too slow-paced. The comedy is lacking a lot of the time, and there are many jokes that rely on long periods of silence or repetition, or things like hastily animated character sprites moving slowly across the screen, which can be good sometimes, but this show perhaps does it to a fault. The animation is fine, but having become accustomed to newer styles and HD visuals, it looks really dated.
Much of the comedy requires knowledge of Japanese culture, which is fine with me, but may be off-putting to some viewers. I was lucky to watch this as my first anime, because I may have dropped it otherwise due to it's slow humor, and jokes that seem like ripoffs, but are, in fact, the originals, because this show is OLD, or, well, old for a school-life anime.
But the reason I like Azumanga Daioh isn't because it is funny. I like Azumanga Daioh because of the loveable characters, and the emotional moments, highlighted by some of the best music ever to be paired with anything. When some actual semblance of a plot begins to form in the later episodes is when the show really wins in my book. One of the later episodes has probably my favorite moment in any anime ever. The last episode brought me to tears several times. Due to the off chance that somebody reading this may not have already seen it, I will say no more about this. Watch it if you haven't. I recommend it to anybody who likes the slice-of-life genre.