SAO's main problem is its pacing. The series tries to jam several books worth of content into 25 episodes, subplots included. A major climactic battle will be shoved into half an episode, right after a filler episode about helping a character that - while charming - doesn't have an important part in the overall story. SAO should have made a choice that it refused to make: Focussing solely on the main arc, or only telling a few book's worth of story like 'The Melancholy of Haruhi Suzumiya' did.
Of course, not all of the pacing issues are just from the size of the source material: the series can't seem to fit in time to develop antagonists, but have no problem dedicating 10 minutes of several episodes to creepy fanservice that feels so degrading as a female viewer, it alone is the reason I marked this series down from a 7 to a 6.
Ultimately, SAO was a decent romp, but so much opportunity was missed thanks to the way the adaptation was handled. Being a lover of JRPGs, science fiction, and romance, this had every opportunity to be one of my favorite series had it been handled better. Instead, Sword Art Online is just another anime that was good enough to watch all the way through, but not good enough to really care about afterwards.
