9/10 - Some parts really disturbed me, the pacing felt off at times, but overall very, very good.
Spoiler for Talking about the ending mostly - Spoilers:
I felt like the ending was very brutal and hard to watch at times. I feel like if you're going to recommend this series to someone, warn them about the sexual harassment/assault in the second half. The payback was really satisfying for me, though it might be too much for some people regardless. If I came across a villain like that, I would instantly kill them without remorse, and it shocked me that Kirito didn't, it really did. And yet, everything ended on a positive note.
For everything else, I appreciated that this series were so close to actual MMO experiences, even though our real technology not being there. It explored some topics that I haven't really seen being explored in anime. I also liked while it explored the really dark side of MMOs, it had this light in the end of the tunnel. It's not the technology that's bad, it's how it's used. I don't know how everyone else feels but I strongly connected Kirito and Asuna, also with the little sister, minus the borderline romance she nearly had with Kirito.