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.
Adaptation Displacement: Like it says above, few people are aware that the games were originally based on a comic book. As far as the adaptations themselves go, the first game is often mistaken for an N64 exclusive.
Even at that, the games seem to be a separate continuity from the comics they're based upon and are likely separate from the rest of the Valiant/Acclaim universe. The first game was adapted for the comics but condensed to one issue and the second game released after the comic division was shut down.
Anticlimax Boss: Although the PC version jacked up the difficulty quite a bit, Dr. Batrachian is still this in all versions for deciding to take on an immortal voodoo warrior with naught but a PR-24 baton.
Breather Boss: Avery Marx is, despite his long and creepy build up, perhaps the easiest of all of The Five to defeat. He does little damage, makes no effort to dodge even a full frontal attack, and has a pretty low damage threshold.
Crowning Music of Awesome: The musical scores for both games are fantastic, but the first is more memorable for being extremely frightening at times.
Demonic Spiders: The Sisters in the fire temples, due to the fact that they can fly and routinely do this over areas that will kill you until you get to the end of the level.
The piglike bondage freaks that show up everywhere in the Asylum. The rifle-toting versions aren't too bad, but the ones carrying meathooks and chainsaws will mess you up quick if you aren't careful, and the chainsaw wielder also carries a bloody human torso as a shield, which you have to destroy before you can damage him.
Game Breaker: The SMGs make bosses a cakewalk, thanks to the high rate of fire putting them in hitstun indefinitely. It only sees use against the Five, but it still takes a lot of the challenge out of it.
Goddamn Bats: The Wailers and Shiverers attack Shadowman by draining his life force from a distance. The good news it that destroying them with the Shadowgun gives back whatever they stole. Duppies and Deadwings are also a huge pain in the ass for their ability to spit giant loogies from a distance and -for Duppies- rapidly shred you to pieces up close.
And in the sequel, we have small flying demons that will either zip around in the distance shooting energy beams or fly in circles around Shadow Man and claw at him. "Pain in the ass" is too kind a phrase for these hateful little shitstains.
Asylum Butchers in Deadside, wild dogs in Liveside.
The voice acting. The sequel manages to make this even more ridiculous. It's not so much that it's bad, but Shadowman is a pretty ridiculous Large Ham and all of The Five except Jack the Ripper are really narmy.
In Avery's tenement several rooms contain Avery's victims and clips are shown of them being forced to repeat Mark 5:9 while pleading for mercy. That isn't this trope. Some console adaptions missed out on this content, but didn't bother to remove the clips which are now just 10-15 seconds of staring at an empty chair. Real scary.
Jack the Ripper. During his boss fight, he prances around like Mick Jagger, talks in a cockney accent, and one of his regular taunts is to "make a Mary Kelly out of you!", but somehow he manages to be the scariest of The Five.
Porting Disaster: The PSX version is pretty god-awful for a number of reasons. The graphics are absolutely horrible and even more content is missing than in the N64 version, but the worst thing may be the constant disc reading it has to do, as the game is constantly loading while you play it. The Playstation's laser motor practically groans under the strain.