The premise, and first couple of episodes, are fantastic. It's a really cool idea. I wasn't even that big into MMORPGs but I bought into it.
***SPOILERS TO FOLLOW***
But that's about where it ends. Much the way Gurren Lagann threw their whole show out the window and basically restarted halfway through, SAO does the same. They reach about halfway to the conclusion of the plot, then decide to end things prematurely and change from an interesting show (albeit with a lot of filler) to this weird creepy real-life situation with incredibly creepy and incestuous themes/overtones. The fanservice is ridiculous and unwarranted, and frankly it feels rapey.
In conclusion, if you enjoy MMORPGs and wish your sister had the hots for you, you will love this show. If you don't, you'll have the craziest blue balls when about halfway through they abandon the premise to focus on what is and isn't acceptable for a sister to feel about her brother.
