Broken Base: Some people were skeptical that The Chinese Room was developing this game, this mostly came from fans who didn't like Dear Esther. Many of the fears, though, have dissipated when Frictional Games said that they are still going to be the publishers
Once the game came out, changes to mechanics brought this issue up again, see They Changed It, Now It Sucks below. It seems another source of debate is whether Frictional should have had given The Chinese Room as much as they did in the final product, and if it makes the game better or worse.
There is also a group of people that are miffed about how the game doesn't feature the changes that Frictional promised. The monsters don't really act much different from the ones in the previous game. And the promise that monsters don't disappear doesn't even matter much since there are only a few in the game. Also despite promises to make the game more open, the end result is very linear compared to The Dark Descent. Again, whether or not if these changes were for the best or if they were because of The Chinese Room's influence is a heated topic.
Critical Research Failure: Mandus apparently got the Pig Mask while exploring an Aztec temple. But pigs aren't native to the Americas (peccaries are, but the mask clearly depicts a domesticated pig), and the design on the mask is very much not Aztec. It's more similar to Haida designs from North American tribes, which is a pretty big distance to get wrongnote The Haida are from the North Pacific coast, in British Columbia and Alaska, very, very far away from the Aztec . For a game that obviously spent a while on researching industrial England, this seems less like a mistake and more like "Screw it, make it look foreign and intimidating".
Fan Nickname: From the teaser trailer alone, the pig monster earned the nickname of Piggeh.
Genius Bonus: At the beginning of the game, you pick up a phone and the caller says: "Precious eagle cactus fruit...help us." This could come across as a Big-Lipped Alligator Moment to those who are not familiar with the term; it's apparently a reference to Aztec sacrificial rituals, in which the victims' hearts, cut open from their chests with flint knives, are sacrificed to a god named Uitzilopochtli. Read more here..
Hype Backlash: Many fans of the original were naturally excited when the sequel was first announced. Upon the game's release, fan reactions became... mixed at best. See Broken Base for details.
It's Short, So It Sucks: This game clocks in at about 3 1/2 hours of gameplay, which was about half of the original Amnesia. Because of this, and the removal of an inventory, many fans have felt that this game is more linear and doesn't encourage you to explore nearly as much.
Narm: Mandus's journal entries are written in an often epic, pompous style that comes out as unintentionally hilarious - and makes you doubt if he's really serious about saving his sons.
"How can a man shit so much blood and still live?" Sounds more like something you would hear from South Park than Amnesia.
On a similar note, Mandus's threat to the Machine.
Mandus: I will rain excrement into your very soul.
The Engineer, post reveal, can really seem like this, with just how hammy he is sounding, more comical than threatening.
The Engineer: MORE PIG! MORE PIG!
Also the fact that The Engineer's ultimate plan to take over the world with an army of manpigs sounds, on paper, like something from a Silver Age comic.
Given the natureof the game, whenever Mandus mentions sex in his journals, it's hilarious. But when he mentions them in unnecessary detail and it's completely irrelevant, then it's just ridiculous. And since not every gamer is an English Major who would know what the hell he is saying because of the old-fashioned and industrial terms he's using, it's easy to misinterpret them as something else entirely. Or, if you wanted to read the easier understood detail about Mandus' and Lilibeth's wedding night by her "summoning him into manhood", then there you go.
"September 28th 1899: 'Imagine', they say 'a machine one day that might think like a man!' As if this is to be desired. One might almost boast of creating a man who breeds like a pig. Men and women upon all fours, rutting carelessly, ejaculating their filthy little missives into the streets. Alleys and gutters running freely with the careless spill of their conjoinings. The air thick with the whimperings of lust. Bodies streaked with their own emissions. We have created a world where man is so utterly debased he will spray his seed over passers-by. And yet, this is the condition Babbage aspired to."
"December 23rd 1899: I stand and look at myself in the mirror, penis in hand, [...] And thus I wash my hands and take to bed."
Shocking Swerve: It seems like the scene after Mandus activates the machine, and The Engineer releases the manpigs onto London to bring about The End of the World as We Know It has been getting this reaction from fans, especially those who were used to the subtlety of the game up to this point.
Many fans have been outraged by the removal of the sanity effects and the inventory.
That, coupled with the roughly 3 1/2 hour play-time (barely half of the first), has also led to lower ratings.
Ugly Cute: The pigmen aren't as deformed as the creatures from the first game, they just look like some kind of vaguely humanoid pig animal. Murderous grotesque perversions of nature though they are, they can be seen sitting at a table to eat messily or playing children's toys, which gives them a surprisingly sympathetic child-like innocence.
Uncanny Valley: The manpigs invoke this trope, not so much by their appearance, but by the way they move. When you see one for the first time, its stooped, three-legged gait makes it hard to tell if it's an animal that has been turned monstrous or a person that has been turned animalistic. It's a minor Wham Moment when you see one standing up for the first time, revealing that they are indeed fully humanoid.