It was awesome at first, but after four or so episodes, it turned into complete garbage. Even the creator of the series said that he didn't plan out most of the story, because originally he wanted it to be a loe story between Kirito and Asuna.
Kirito is basically a mary sue, who is entirely overpowered and unliakable. Between him and Natsu, I think he takes the cake as the worse MC. Basically, all these females fall for him without reason and the game system was entire crap. Plus, the villain of SAO was entirely the WORST villain I have ever seen. He said that he forgot why he created that situation, which is beyond retarded.
This along with Fairy Fail, Asteric War, and other crappy Ecchi, child porn series are the reason why a small part of me hates anime.