WARNING: RANT AND SPOILERS INCOMING!
I didn't like SAO at all. The character developments and plot were horribly done, which is disappointing due to it having so much potential to be a great anime. Firstly lets talk about the characters. Kirito is just a wish fulfillment character and nothing more. He is overpowered for no reason at all and apparently is so bad-ass that every girl he meets for the first time falls in love with him ( not to mention that he have to save their ass every single time before they fall in love with him ). Asuna was introduced as a mysterious strong female lead in the beginning and showed great promise but turns out to be your generic tsundere. Her romance with Kirito was so poorly written that I literally face palmed. The antagonists lacked any kind of motivation at all. Why did Kayaba trap all the players in the game and implemented a death mechanism? Because he was bored?! Kuradeel was just plain stupid. The side characters were all quite similar in a sense. They all get one or two episodes each ( which served nothing for the plot) , and then gets thrown away and forgotten until the last episode where they get some screen time. Enough about that, on to the plot. The most obvious flaw: the pacing for the story was terrible. They condensed two whole years of time in 12 episodes. That would have been fine if they spread it out evenly, but no. In episode 1, every player was level 1. One episode later, they were LEVEL 46. And then what did they do with they extra time after the time skip? Fill the gap with filler episodes. What the hell?! Also, the writing was so poor that the author needed to CONSTANTLY pull a deus ex machina. Whenever Kirito is in a pinch, he suddenly becomes jesus and defies logic to save the day. All in all, the only good things I can point out about SAO were the music and animation. Oh man, I'm gonna get so much hate for this.