Least favorite part (spoilers)

[TwoCatsYelling]

I'd disagree about Phi. At that point, the game is over, and the only thing left to do is launch the ARK. Sure, they could've made this a frantic sequence where you are racing against the increasingly growing WAU army as they charge down your doors, but I feel like that would undermine a lot of the tone that the game has been striving toward. Instead, Phi is meant as a place where Simon can finally have some peace of mind as he accomplishes his mission, gets on board the ARK, and launches into space, leaving the hell hole that is Pathos-II behind. It also serves as a nice point of stark contrast for the moment when Simon realizes that he isn't actually getting onto the ARK, that he is, in fact, trapped on Earth. It's one of a lot of factors that go into making that ending have the punch that it has.

Yeah, it was kind of a nice, extended "breath of fresh air" arriving there. Though I kept expecting something to go wrong at any moment, as I progressed, I realized "okay, I think the worst is behind me".

It was a nice contrast, after the darker and deeper hell you'd just gone through to revisit some place that was, largely, unaffected by the WAU and still holding together, well lit, etc.

To answer your question, though, my least favorite part of the game is the post-elevator tunnels of Theta. It's a dark maze where you have to follow the same formula over and over again - hide in the dark, find the way forward, hide from the proxies, solve a puzzle that involves making a lot of noise. It felt like the laziest part of the entire game, made even more tedious by it being the third time in a row you've had to deal with this kind of monster. It's in this part where you can really see the internal dichotomy that rages throughout SOMA's philosophical design come to a head - the split between whether to make an atmospheric horror (a la Amnesia) or a psychological thriller. These two directions are constantly at odds with each other throughout the game, so much so that when the focus switches from one to the other, the change is abrupt and drastic and it undermines the weight of the moment while you're recovering from the mental whiplash.

Same here. The post elevator bit made Theta overall seem to drag on too long. It also felt the least, hmm.. "coherent"?... to me. I honestly did not know what I was supposed to be doing and found myself going in circles for a while, just avoiding that frankly annoyingly ever-present enemy that was everywhere. Rather than feeling moments of "a ha!", the post-elevator bit felt more like accidentally stumbling my way through it. The area toward the end was fun, though, reminded me of some of the deeper areas of Portal 2.

I finally got to the point of using the 'wuss mode' mod just to get past it uninterrupted, because I was starting to feel frustrated at how long this section of the game had been dragging out; knowing me, when frustration firmly sets in, I lose interest in continuing at all. I feel like they could have greatly shortened that bit, especially with how long the combined previous segments were. Maybe one final encounter with it, a la Curie and Omicron, and then move on. I generally don't like using 'cheats', as I like to experience a game as the devs intended... but Theta brought me dangerously close to saying "forget it... this isn't fun anymore", which would have been a shame, because SOMA is an incredible game. So, 'wuss mode' basically "saved" the game for me in this case.