**NO SPOILERS HERE**
I come from playing a long list of MMO's, so my viewing is a bit biased.
I felt from the beginning of this show the goosebumps rise all over my body as the characters first stepped into the Sword Art Online. I loved the entire story from start to finish. There were so many twists and deep storytelling. There was one part I didn't like later in the show when there was a BIG TWIST, and you will know what I'm talking about when you get there, but besides that I loved every second of it.
The characters were amazing. I felt so much emotion from all of them. The relationships felt like they were deep and true.
When I watched this show I felt like I was in another world along with the other characters. Once I started watching this show I couldn't stop. I ate way too much one night and should have passed out, but I stayed up because of how addicting this show was.
This show is truly now my favorite and it may be the only anime I will every re-watch. If you are an MMO fan at all then do yourself a favor and watch this show.