I started SAO II because hearing so many people saying it would adapt arcs that are vastly superior to the previous ones made me really curious about how far this franchise could go, and I bet wasn't the only one. As I bet that I'm not the only one who was left absolutely, utterly disappointed (but not surprised) upon seeing all of the same old bullshit that made the first season so terrible repeating itself.
This review may contain spoilers from now on.
Sword Art Online II adapts two arcs from the novels: GGO and Mother's Rosario. Oh no, wait, it's three arcs: there's also the Calibur arc - hard to remember it even existed considering it lasted for about three episodes and had no relevance to anything at all. But again, is there even a point to anything in this show other than showcasing how amazing & powerful Kirito is and adding new girls to his harem? I guess not. SAO remains what it is in its core: a self-insert show with childish writing scattered everywhere.
Let's talk about each arc individually. The first one, GGO, is the least weak of the bunch (not that this means anything when all of them are bad). It features Sinon, a new member of Kirito's harem - I mean, heroine, as well as a new setting. The fact that they cast aside an entirely underveloped cast of characters to introduce a new girl should already be stinky - but as if that's not enough, GGO is very sloppily written. They use the most ridiculous excuse to connect the current events to events that happened back in the first arc (I mean sure, the laughing coffin members murdered people 'n stuff, but it makes all sense that they're still out in the loose and not in jail!), as well as a MASSIVE amount of stupidity such as "People are getting murdered inside of a game again? Well geez, I guess our only solution is sending in this 17 year old all alone to investigate this!" The logic in this arc is piss-poor, and as anyone can guess, everything is resolved by Kirito finding out all by himself how the villain was working and who he was, with little to no base at all. I mean of course, Kirito is so awesome he figured everything out by himself! It made all the attempts made in the very same arc of giving him flaws and depth a complete joke. This arc's main antagonist is also a pathetic piece of turd with terrible characterization - you know something's wrong when a villain's entire backstory, motives and goals are explained by the protagonists while they're chatting and having coffee.
Calibur may as well be summed up in a single phrase: What was the point? It features the "main cast", if they can even be called that, clearing a quest in ALO. And yeah. That's all. It feels like really, REALLY bad filler, and I have nothing else to say about it.
Moving on to the last arc, Mother's Rosario: it's an arc where Asuna is the protagonist, along with Yuuki, another newly introduced character. To put it shortly, this arc will do ANYTHING to make you cry. It's as if the writer was noticing that he didn't look "mature" enough with the whole in-game murder thing and thought to himself "I need to add some more drama to this". So cue Yuuki's storyline - no, cue Yuuki's entire character, who was designed to make you cry with the whole "My whole family is dead and I have a terminal disease" thing. Predictably, they deal with this in a very insensitive way - it's not organic, it's not presented naturally, it's 100% designed to make you pity her. Yuuki is more defined by the fact that she's terminally ill than by her bland personality, which makes the second time in SAO II where the writer uses an illness as an accessory to earn easy tears and seem mature (the first time being with Sinon's PTSD). But as you can guess, the way it's presented and dealt with isn't mature at all, it's borderline insulting. Mother's Rosario is also supposed to be an arc where Asuna gets developed as her own character, but considering that her biggest conflict was convincing her mother that she was ready to drop everything else in her life to be with Kirito, it only furthered her role as the lead waifu of his harem.
If I talk about the characters it will take me another 10 paragraphs, so let me try to keep it short. Kirito is still the same thing as in the first season: Amazing, cool, incredible, smart Kirito, who finds out the truth behind serial murders by himself, cures Sinon's trauma by himself and is apparently also a mechanics genius who can make video game characters see the real world. They try to give him depth in GGO by showing that he's truly traumatized by the events of Aincrad, but it backfires horribly when right after it's shown that he's a "strong person who keeps moving foward regardless", a.k.a. he can get over it quite easily if the plot calls for it. They also tried to give Kirito a goal in him striving to unite the virtual and real world as one, but it backfired again as it's clear that nobody gave it enough thought to realize how stupid, dangerous and almost villainous this sounds. His smug-ish attitude towards Sinon also remains unchanged from the previous arcs, so don't worry, he's still an annoying prick on top of being a terrible self-insert character.
Sinon had everything to be a good character, as she's the first heroine in this show with a palpable personality, but they sacrifice it to make her the tsundere that was missing in Kirito's harem. They use her being understandably wary of him as an excuse to make her act tsun-tsun. There's also her backstory, which could have been good if the writer had even a slight idea of how panick attacks and PTSD actually work instead of getting them triggered whenever's convenient to the plot. Her character development revolves 100% around Kirito. Sinon's role in the show is defined by the moment she says "Someone, please save me" in episode 3: she wasn't there to be a character who learns to save herself and grows in the first place, she was there to be saved by Kirito and later fall in love with him. She was there to be nothing more than another disposable harem member disguised as "strong female character". In the end, Sinon is no better than Asuna.
Speaking of Asuna, she succeeded on having the most bullshit "character development" I've ever seen. Introducing her family out of nowhere and sparkling conflict with her strict mother wouldn't have been that unacceptable, really, if at least she had something to fight for herself, but it doesn't count if said conflict is her mother not wanting to let her ruin her life getting married young (to Kirito, of course). Asuna's entire character arc isn't about her growing as a person, it's about strengthening her resolve to get married to Kirito - as IF she needed that, considering that her entire character is defined by her love and devotion for Kirito in the first place. Mother's Rosario did nothing for Asuna as a character as much as it did for her as a "waifu". She will probably be even more loved by otaku now that she fits the "perfect wife" stereotype better than ever, but it sure as hell doesn't make her well written. She, Kirito and their sappy romance remain as flat and unsavory as ever.
I could write about the other characters if there even was something noteworthy to say about them. Suguha was dropped into limbo after ALO and has no relevance in the second season, but that's to be expected - if you're a female character in SAO, you only have two jobs: Falling in love/getting rescued by Kirito in a certain arc and providing fanservice. After that, it's as if you never even existed in first place. The only thing I can say about Suguha, Rika and Silica (and Sinon after GGO) is that the way they get angry at Kirito for getting attention from Asuna is extremely immature, annoying and unfunny considering that they are, you know, engaged. But again all the comedic moments in SAO sound like they were written by a horny 13 year old boy, so I guess it's nothing new after all.
I don't have a lot to say about the animation except that in some scenes it looks pretty good and carefully done and in others it's literally slideshow bullshit (look at the first Calibur episode, for God's sake). Overall, it doesn't look bad. The sound is ok, too. None of it is bad, but also not good enough to even remotely come close of saving anything in this show, so I won't even bother talking about it any further.
Well, now you can downvote me to your heart's content.