Manga Season 2: More of the same, except somehow worse
Everything wrong with the first season of Sidonia is present in the second: janky animation, characters who behave inconsistently even within a single scene, laughable attempts at "drama" by naming random disposable clones sometimes literally seconds before they die, a pervasive feeling that both the characters and plot are ambling aimlessly through the setting. The second season breaks new ground however by managing to be even more inept than its predecessor.
Sidonia has no idea what it wants to be as a show or about. The second season starts out promisingly enough. Several characters are infected with some kind of sinister mindworms! There's what might be a coup! A massive colony ship that looks to be a third the size of Sidonia has been completely subsumed by the Guana!
...And then it just drops everything about midway through in favor of being some sort of passive aggressive harem anime, where the majority of female characters are drawn magnetically (and inexplicably) to the appallingly bland male lead, whose personality is so forgettable that even writing his name would give him more credit than he deserves.
Said lead for his part spends multiple episodes obsessing over a space monster which I can only attempt to describe as Saber from Fate/Zero made out of a shrimp cocktail, who speaks through a giant flexible penis of arbitrary length and acts like a high school freshman. Oh, and sometimes Not!Sephiroth or his submissive female servant sit in its skull, musing sinisterly to themselves about nothing in particular while dressed like space Nazis. It's even more surreal and moronic in execution.
There are also several interminable sequences where it looks like the protagonist is about to connect romantically with one of his many female admirers, but nothing comes of them. Nothing ever comes of anything in Sidonia. Even the penis monster.
Eventually the plot (and I use the term loosely) remembers that there are space monsters which its cast ostensibly fights, with two episodes left to go. There is an admittedly pretty cool battle sequence, more last minute romance bullshit that goes nowhere, and that's a wrap. Mindworms, space colonies, Sidonia apparently now being ruled by a military junta? All unceremoniously dropped. I guess they're banking on a third season. I look forward to it!
Manga Amazing fights. Boring characters
I've watched most of the anime series with the exception of the last few episodes and I can safely say this. If you just want to watch giant mecha zip through space as they fight massive monsters then this show will deliver. If you're looking for engaging characters though, this series is rather disappointing. In fact the plot in general is both lackluster and boring.
First things first. The series is all CGI, which is both a blessing and a curse. In the fights it allows the mecha to do amazing things. In fact the fights are some of the best I've seen in recent anime. With the way the mechs zip through space fighting monsters that have no static shape. It's very fast paced and very exhilarating. The series also feels like it has a very hard take on space combat (For a show that has mechs anyway) with the way that the mechs have a limited range and can't stray too far from the main ship, or else they won't have enough power for the return trip.
But when there aren't any fights, we're stuck with the characters interacting, and they are beyond underwhelming. The CGI really bites the series in the ass here, not only do all the characters look stiff and unnatural but there's barely any defining characteristics when it comes to their design. There were two black haired women and it was only after one died and the other one was still alive did I realize that they were different people. And even though the series has such a massive cast I honestly can't remember the name of a single character a couple of months down the line. I can't even remember that many noticeable personality traits of any of the characters, just that the main character is a kind of generic nice guy and there was also a platinum blond prick. There should not be boring characters in a series with a talking cybernetic bear.
The plot is just...eh. There's no long term goal for the characters other than "Kill monsters and don't die". There's nothing for them to aim for and it just makes all the fighting seem pointless. There's some sort of conspiracy going on with the council of the main ship wanting the main character dead because he's the clone of one of their former members or something but really there's nothing engaging about the plot because there's not a single reason to care about the characters.
On a side note, the music is really good.
Manga It's like Attack on Titan, In Space! And terrible! (Anime review)
As a preface, I am fully aware that the manga for Sidonia came out before Titan.
Knights of Sidonia is one of the worst things I've ever watched. It's also one of the most entertaining. The show is desperately awful garbage for three interrelated reasons:
1. It looks terrible. The anime is completely computer-generated and has the appearance of a circa-2008 MMORPG run on a PC with a dying internet connection. For reasons beyond my comprehension, Sidonia has what I can only describe as severe framerate issues. Characters are deep in the uncanny valley, jerking and bobbing like corpses on strings.
2. It's impossible to relate to or care about anyone. Not only does the cast resemble ineptly-piloted marionettes, but they have backstories and motivations which defy conventional thinking. Most of the characters (and there are a lot of them crammed into a paltry 12 episodes) are explicitly identified as being expendable. They're interchangeable, nigh-identical cogs devoid of all but the most basic character traits ("coward", "duplicitous asshole", etc). Most are clones (not a spoiler past the first episode) and conduct "photosynthesis" despite being pale-skinned and living on a ship apparently illuminated by massive fluorescent lights. Dozens of people are introduced and then immediately killed, for zero emotional impact. It's moronic, and brings me to my third point-
3. The plot is incomprehensible nonsense. Hardly anything that happens in the show has a rational explanation. There are a half-dozen random subplots going on at any given point and none have any payoff. It doesn't help that the show constantly uses jargon never translated in the English subs. The good people of Sidonia appear to be only vaguely cognizant of their own mission. Thousands die on multiple occasions and are casually forgotten by the next episode.
All that said, this show is definitely worth watching. It's a laughably bad trainwreck from start to finish. I recommend bringing a friend and some beer. You'll likely need both.