SAO:Extra and the SAO franchise is a strange case for me. They definitely don't have the best story or characters by any chance, but still manages to be incredibly enjoyable. Although reading the light novels do help with this, since the series does feel rushed. I really don't know how they do it.
Keep in mind that you should watch the original SAO before watching this series.
I came into SAO:Extra knowing it would probably have many flaws, but still eagerly awaited its livestream. It's sorta like cocaine.
Story: 4/10
This 2 hour special involves 1 hour and 40 minutes of recaps from the original series, showing past events through flashbacks from various characters. I must say even though I have watched those scenes before, it was still enjoyable. You can hardly account that as a story though.
However, through those flashbacks and reflections we did get to see some emotions and feelings of some characters in specific scenes which we did not get in the original series. These emotions were described in the light novel, but the anime (which had a very rushed feeling throughout) missed it out. An example is Asuna's recaps on how she first met Kirito, and what she was feeling during the events that unfolded. A nice addition for people who haven't read the light novel, or people who really like scenes that just tell you character's feelings instead of leaving you to guess or intepret.
The final 20 minutes brought a new, original story although I can tell you, it isn't much. I hate deus ex machinas and crappy endings with a passion. With that in mind, the ending is a shitfest of old nappies and dog poo, cos, it's just bad.
Keeping in spoiler-free, it involves a badass boss fight which is just beginning, when some other NPC boss comes in and tells the other dude to fuck off, end of movie.
I'm not joking.
Art: 9/10
I enjoyed the art of the original SAO, so naturally the art here is spot-on here too. Mizugi errwhere to bring in the 12 year olds.
Nothing else much to say here. A lot of scenes were cut directly from the original, but the new scenes have a "real-world" setting so it's not like you can see Asuna in her KoB uniform or anything.
I mentioned Asuna a lot huehuehuehue
Sound: 7/10
Giving it a 7 because there is only 1 new song for this special, which plays at the end. Definitely good enough to download, but because the show that went with it was not as effective, it didn't leave much of an impression. Lots of reuse of crossing field, overfly, innocence and yume sekai.
Character: 7/10
All the characters fill their respective personalities well, with some variances (since they're living in the real world now anyway). Asuna in the real world is very mature and composed, which gives you an idea of how she lives when she's not in a death game (lul, talking bout Asuna again).
There was quite a lot of development of Lizbeth's character. She's actually quite a fun and teasing character which is enjoyable to watch. We didn't see that much in the original show, she was sort of just there for another girl that wants Kirito's D (must be fucking gold in there).
Kayaba Akihiko is a character that always fascinated me, and the recaps resparked my interest in the philosophical views regarding the morality of treating sentient AI-units as humans or computers, the theological views on God and man relationships, and the psyche which Kayaba had which made him create the death game world that he did.
Enjoyment: 10/10
SAO always does this to me. A show with many flaws but still a highly enjoyable and beautiful journey. I love the scenario, story and characters no matter how cliche and Mary Sue it was. I love delving into the philosophical outlook on the repercussions in an alternate society, and Kirito and Asuna are always enjoyable to watch (esp. Asuna)
Overall: 7/10
Just like MAL captions, it is "good". The story is not so much "needed", but is a great addition for fans. Watch this if you enjoyed SAO, and continue on for SAO II coming out later this year!