Sword Art Online is an anime with the premise that a fully immersive virtual reality video game has been developed, and thousands of people put on the Nerve Gear to play it... only to find that they can't get out of the gameworld, and if they die in the game they'll die in real life. The only way to get back to the real world is to defeat the final boss on the 100th floor. Sounds like a good premise, doesn't it? And the first episode was indeed really good. Unfortunately, however, the show is garbage. Here's a list of major problems with it (I'll mark significant spoilers):
It's the definition of a harem anime. Centered around the show's Gary Stu hero Kirito are twelve-plus female characters, almost all of whom are sexually attracted to him. Besides villains, there are no other major male characters in the show - Recon is only around for one arc, Agil averages about one line per episode, and Klein is just comic relief.
Absurd levels of wish fulfillment. A Gary Stu protagonist with a Mary Sue action girl for a girlfriend is one thing, but when they decided to give the teenage couple a five-year-old daughter out of nowhere and completely pause the plot to bask in it - only to kill her shortly after, but not really, because they couldn't bring themselves to actually kill off a character in this show that derived its entire premise from that threat, so they had Kirito pull yet another Deus Ex Machina to make a backup of her - it just got disgusting.
One of the lamest imaginable cop-outs to get the heroes out of trouble. In the scene where Kirito and Silica have just retrieved the pet revival item or whatever and the laughing coffin players ambush them, I was actually excited and curious as to how they were going to get out this. Boy was I in for a disappointment. They don't need to do anything clever because he's so high leveled that six or seven other players can't even damage him faster than he regenerates even if he doesn't defend himself. This is even worse than a typical Deus Ex Machina because if you take this scene as canon, it not only ruins itself but gravely harms the future of the story. Shouldn't any character Kirito meets after this be a worm to him? The writers either didn't realize the destructive implications of that scene or decided to quietly retcon it, because Kuradeel was able to kill him (would have if Asuna hadn't showed up).
Literally going back on what the audience directly saw. Are you fucking kidding me? Kirito got stabbed, his health clearly reduced to 0, but then he just stabs Akihiko Kayaba back and wins the fight... and lives. Having him win the fight is fine, but at least don't show us the defeat screen first.
Anti-retributionist bullshit, and I mean the kind even most non-retributionists would recognize as bullshit. In the Phantom Bullet arc, they have Kirito feel that he somehow needs to 'atone' for killing two MURDERERS that were not only uncontainable but TRYING TO KILL INNOCENTS at the very moment. Even if you don't believe in the death penalty, there is absolutely no argument to be made for that.
A computer program is portrayed to be a person. This is a logical impossibility.
Goddamn that mythology mini-arc was pointless. Not only would I have not known if those two episodes had been cut out, but there were no stakes. Even if I liked the characters (which I didn't), I wouldn't want to spend 40 minutes of my life watching them complete a video game quest and not even develop as characters in the process.
Little to no stakes throughout the final arc of season 2. We all know the sleeping knights are dying and the objective isn't to save them. It's just to beat a boss in a video game. They could have used the opportunity to give Yuuki an existential crisis and have her decide to do something meaningful with her last few days of life, but nope.
A plethora of nudity and other sexually pandering scenes, including those featuring Asuna, Sugu and Sinon in their underwear or in Sugu's case, completely naked (luckily obscured).
Timeskips. One month skipped after the first episode (really?), and then years skipped after that... precisely so that they can develop the characters without us seeing?
Villification of a character who has a point. I am talking, of course, about Kibaou. While he's wrong to demand that the beta testers give all their stuff to the blind players, the beta testers really did behave selfishly. They owe at the very least an apology.
Simple plotholes. This article details a bunch of them. I'll go ahead and add that Kirito had no reason to keep his dual-wielding ability a secret. Not to mention that I don't remember it ever being explained how he got it in the anime (the ability just appeared in his inventory one day and no other player has it) but according to the wiki it's explained in the manga, leaving it unclear if I just misremember or they took out the key scene for the anime.
Pulling a villain out of nowhere in the Phantom Bullet arc. They built up so much anticipation around the reveal that Death Gun was someone Kirito knew from Sword Art Online, but after all that it wasn't a character the audience had seen. Absolute failure.
So what's the good news, you ask? The only good news is that you don't have to watch this show. You'll regret it. But now that you've read my article, you know that, so you can spare yourself the trouble.