I am going to moderate my earlier harsh criticism of the show. The second half of Sword Art Online is much better than the first half, which may reflect a gradual improvement in the writing skills of the young author Reki Kawahara. On balance SAO is a lightweight but entertaining story, though it is not on the same level as Accel World which is based on a later work by the same writer.
The first half was all about Kirito, who by himself just isn’t a very interesting character. The second half opens things up by adding other major characters. There’s Asuna of course, who only had a walk-on role in the first half. Then the second arc adds Suguha who is actually the most interesting and complex character in the series. Yui and Recon are minor characters but they add interest.
The first story arc has a villain who vanishes after the first episode and remains offstage until the very end. The Alfheim story arc has a much more entertaining villain who has the decency to show up every so often and reveal new heights of evilness. More importantly, the Alfheim arc alternates between the real world and the game world, making it clear that events in the game world have real world consequences. (Sure, we knew in theory that events in the SAO game could have real consequences, but since we never saw the consequences it didn’t have much emotional effect.)
It doesn’t hurt that the second arc seems to have a much better game than the first. The SAO game world was a collection of all the hoariest RPG cliches. Alfheim Online is a more original game. (It also seems much more plausible that it would attract female players.)
Now for some random speculation. If you’ve watched both shows you know that Accel World is set in the same universe as Sword Art Online, about 20 years later with improved technology. Knowing how the typical author’s mind works, that suggests to me that the mysterious creator of the “Brain Burst” program in Accel World must be someone we met in SAO. Who could that be?
- The cyber-ghost of Kayaba. That’s the obvious guess and suggests that Haruyuki and his friends are in for a nasty surprise.
- Sugou. An even nastier thought, but he doesn’t strike me as smart enough or subtle enough to do it.
- Kazuto. Maybe if his game obsession led him to become a game developer. But probably not. Brain Burst is obviously illegal, or would be if the authorities knew about it. Asuna wouldn’t approve, so Kazuto wouldn’t do it unless something happened to Asuna.
- Asuna. No, she just isn’t the type.
- Suguha. Only if something happened to Kazuto.
- Recon. Actually a good prospect. He’s a game nerd and disappointed in love.
- Agil. Probably not. He seems a permanently minor character and he’d be pretty old by the time of Accel World.
- Yui. Now there’s a disturbing thought!