These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Acceptable Targets: Surprisingly, despite the majority of the enemies being Soviet soldiers (either past or alternate-present), most of the recordings and flashbacks do quite a bit to humanize the Russians in general. We see recordings of a couple deeply in love, leftovers of friends playing chess, teachers taking care of schoolchildren, and so on.
However, the evil masters of Katorga-12 were also intentionally exposing the children to E99 by putting it in their milk just to see the results, so while the people in general were human beings, the Soviet war machine was definitely run by evil bastards.
Complacent Gaming Syndrome: It's not hard to get through the entire game using only the Valkyrie once you've gotten it early on, especially when you consider how quickly you can upgrade it. The plentiful ammo is also a point in its favor.
Demonic Spiders: The teleporting, phasing enemies which reoccur throughout the game are an absolute nightmare to fight. Even after you get the TMD, which allows you to knock them down for a fairly easy kill, the low amount of TMD energy and the high-cost to Impulse makes it a difficult tactic. They swarm you, in packs of three or more, and can kill you before you can even take one of them down.
And every time you think you've cleared the area, more teleport in.
Then there is that special mutant who appears a couple times who is immune to your deadlock power.
Foe Yay: In the final level, you can find early audio logs by Dr. Barisov and Dr. Demichev where they express the enormous admiration they have for each other. Although the two of them have a falling out when Barisov realizes Demichev is an amoral, power-mad loony, and Demichev realizes Barisov is not. Indeed, it seems Demichev made every effort to include Barisov in his plans for world domination, before finally getting tired of Barisov's Honor Before Reason and deciding to just kill the guy.
Goddamn Bats: Goddamn phase ticks! They usually appear in swarms and latch onto you and explode. Two of the TMD functions can save you from them (the Impulse wave, or the time-slowing Deadlock field) but they're still annoying, distracting, and potentially deadly if you're caught at an inopportune moment.
Paranoia Fuel: The first time you meet the "Echo" Zek, he jumps and takes a stab at you, after which he vanishes. If you have the Spikeshot rifle, you can use the thermal scope to look behind you... and see that he's still there. He stalks you for most of that chapter, and most people don't even know he's there.
The first half hour or so of the game plays out more like a Survival Horror game than a sci-fi shooter. Your helicopter goes down and you find yourself alone on a deserted island where it becomes increasingly obveious that something has seriously gone wrong here. You find only a pistol to defend yourself (along with the knife you start with) and start seeing ghostly flashbacks of what happened along with notes and messages left by the people who died there. Then you get jumped by something that looks like a cross between a zombie and the Slender Man, which you have to shoot off. Then you get to the school where things are even worse... At least its near here that you get some heavier firepower and meet up with your buddy Devlin.
Player Punch: Barisov's ending. As the details start slowly adding up, Devlin, who made himself fairly useful in fights, voiced the confusion the player was likely feeling in the early part of the game and was eventually murdered by Demichev, and is now alive and well, thanks to you, says, "Isn't that right, Comrade?" This moment tells you what's going on before the statue does, and it's your own buddy obliviously saying You Can't Go Home Again.
Special Effects Failure: The 3D modeler who made the Valkyrie had a bit of a brain fart; it has a folding stock, but the hinge is on the same side as the E99 tech sticking out. The stock wouldn't come close to resting flat against the rest of the gun and would stick out so much it would be more cumbersome than anything.