I really liked season 2 a lot better than season 1, especially towards the end.
Story
The characters are back. Kirito joins GGO and solves more murders. Asuna actually becomes the main character at the end as well.
Characters
The same character as before are back in the second season. Sion joins as another girl to ship with Kirito though. My favorite girl in this season was a girl named Yuki though and her story.
Sound/Animation
I liked the opening and ending to this show. The animation was good as well. The second opening is my favorite though.
Verdict
I really liked this season better than season 1. I give this show an 8.5 out of 10.