Summary:

Sword Art Online has a solid premise that theoretically might work as a setting to a apocalyptic world, but feels under utilised in only under 12-13 episodes (lucky we have "SAO: Progressive" for that). Nevertheless, the first half is decent, and the conclusion is bitter in a beautiful way. This series will be 7/10 if not due to second half's disgusting plot. At least we can witness a satisfactory villain whooping.

What I like: first half conclusion and decent animation
What I dislike: basically the entire second half

Details: POSSIBLE SPOILER WARNING
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First arc:

• The initial setting at Aincrad has several untapped potentials. For starters, the stake has been introduced, so it is up to the series to expand how the characters can grow or experience in the setting.
• Since this arc focuses on Kirito, we can see how Kirito cope with the past trauma, losing everyone he cared at the first few eposides. This is a good start in developing Kirito and giving him some backstories. Unfortunately, the other characters are fairly neglected and only serve as either plot device or romantic sideplots (Klein, Liz, etc).
• Speaking of romantic sideplots, the flow or romance is very fast and unnatural (Liz). While Kirito and Asuna's chemistry is decent, Asuna herself is relatively underdeveloped, and she is even more underdeveloped in the second arc.
• On the other hand, the level progression was too fast. I would prefer if the series can slowly go through Aincrad and develop the worldbuilding, if it means we can get to see more of other characters' perspective and struggles. You can argue that Kirito is a beta tester and is a competent gamer, so it is natural that the level progression is fast, but it also makes the story (and Kirito) less interesting.
• The animation is decent, but I felt that a lot of times Kirito is not really creative with his sword movement: on multiple occasions he just slashes with his dual swords ferociously, even to a guy who clearly has a big shield, which I found hilarious.
• Nevertheless, the Asuna-Kirito conclusion is bittersweet, the ending visuals are beautiful, and the final panel where Kirito walks with hospital support is beautiful

Second arc:
- 2 phrases: incest and tentacle rape. This is enough to disgust me. Worse, the series could have been written without these elements. Actually why would they need incest plot? Kirito already "marries" Asuna anyway.
- But on top of that, there are also several issue I have with the series:
1. Kirito vs Leafa: the series has time for this, wasn't Asuna in danger, Kirito? Smh
2. The nerdy guy who likes Leafa, can't remember what else he did
3. Asuna is basically damsel in distress, no room for her to shine
4. Even when Asuna is captured, the stake feels lower (maybe that's why Kirito still has time for Kirito vs Leafa)

• Best character: Maybe Kayaba (Heathcliff)
• Worst character: either Suguha (Leafa) or the boy who crushed on her