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.
Good Bad Bugs: When you're at the Escort Mission part of the game and have returned to Building World, there's a way to teleport Eileen to a part of the map normally inaccessible to her without solving a time-consuming puzzle. Very convenient for speedruns, as well as for those who just want the Escort Mission phase of the game over with.
There's also a random bug which fits the second half of this trope: for no apparent reason, however careful you might be with Eileen, at random points in the game, she might suddenly be fully haunted by Walter. At the very least, though, she can be (temporarily) treated with a Holy Candle, like a regular haunting. This second bug might occasionally coincide with the first, although it's relatively rare for this bug to happen.
Those double-headed baby things. As if their appearances weren't already creepy enough, when you first seem them, they're pointing right at you! One of the scariest parts of the game, in fact, is having to face a grand total of six of them, all at once, in a long corridor! Thankfully, Eileen is with you at this point to help you take them on, but seeing them blocking your way and pointing at you from afar is truly the stuff of nightmares.
A lot of the hauntings are creepy, but the shabby doll one probably takes the cake.
Wow, this is a long hallway, why are there so many doors? Okay, let's open this one — wait, what's that breathi... AAAAAGH, BIG GIANT HEAD!!!!!
And its accompaniment: this sound. (Warning: NSFW audio. DO NOT play without headphones on, to avoid any awkward moments with anyone overhearing this.)
The idea of suddenly being locked in your home, able to observe the outside world, but not contact it.
Most of your time in Henry's apartment will be spent gawking at Eileen and your other neighbors through various peepholes.
At the same time, things will move around in your apartment while you're off exploring other worlds. Two sections of the game are spent trawling through a tiny panopticon. Oh, and both the phone and the bunny are watching you.
There's also the corpse of Walter stashed in a secret walled-off room in your apartment. Sweet dreams!
They Changed It, Now It Sucks: Some fans complain about how the gameplay is quite different from the previous Silent Hill games. You don't use a flashlight, you can only hold ten items at a time, and the game isn't as puzzle-oriented as its predecessors. And it is saddled with the (false) rumor that this is just a Dolled-Up Installment. Though compared to the otherSilentHillgames released after 4, this one doesn't have that much hate as it used to have.