Wasted potential first off, overrated, horrible love story, should not have tried to be a harem, crappy dialogue, glorifying overpowered protagonist gives the show no sense of danger, terrible fight direction, wasted animation budget, unnecessary fan service, poor dub, poor sub, stole VRMMORPG approach from .hack and even made it horrible, many many many plot holes
Alright. The guy who made it has never experienced love or played games ever in his life, progressively gets worse, very bad ending of SAO season 1 that can be seen as cliche and very poorly executed, fans just make it all the worse, unnecessary side stories, detestable characters which are either bland or just flat out annoying, did I mention how bad the plot is? Oh I did. I just can't help how bad it is and how bad it's executed. The beater concept is actually pretty hilarious, tries to be good, generic antagonists
TL;DR: Episode 1 was alright
Episodes 2-end of Aincrad Arc were meh-bad as it went on
ALO was obviously total shit
S2 was better than s1 but still shit
4/10 bad show