Great story, with tons of unique concepts and massive amount of potential from the world that has been built.
Art is good enough to hold your attention, without being the main appeal of the anime.
Sound does it's job. Not outstanding.
Characters are all expressive without being dreadfully bland archetypes. Interaction between the characters is very pronounced. There's comedy and seriousness in their rightful places, so there's no mood killing.
A wild ride from start to finish, each episode keeps amping up the experience by making use of the neato MMO concepts and great characterization that stands above other MMO anime.
Solid 9/10 overall from me. Probably
the most enjoyable anime to come out in the past couple years.