Cult Classic: The games have developed a very strong cult following in the years following their release.
Hilarious in Hindsight: Shannon's unlockable costume in the first game marks the most drastic shift for any of the characters, taking the Girl Next Door and giving her a Hotter and Sexier goth/punk makeover as opposed to just recoloring her existing clothes. The second game has Shannon canonically becoming a goth chick.
The Scrappy: Stan. In the first game, the only reason you even encounter him is because he's inside a room where the key to a locked door is located. While Shannon and Ashley went to find the missing Kenny, Josh tagged along because he had a crush on Shannon, and Kenny joined the party after he was rescued, Stan seemed to join the group simply because he was there and had little better to do. He could've been written out entirely, and the plot wouldn't have changed at all. In the second game, he literally drops in two-thirds of the way into the game following Mei's death with nothing more than a cameo appearance in the introduction, and then gets into a relationship with Shannon and becomes the main hero because of Corey's suicide, with literally zero set-up.
Narm: With the Resident Evil-like voice acting, rather absurd plot, and background music that sounds like a bunch of children making stupid noises, it's pretty hard to believe that the game's actually meant to be scary. On the other hand, one could argue that the background music of Ominous Latin Chanting by a children's choir actually helps to build a genuinely scary atmosphere.
Tier-Induced Scrappy: The characters all had unique abilities, but due to Anyone Can Die, none of them are necessary to complete the game, and furthermore, some are more useful than others.
Ashley's abilities (both a rapid-fire skill and extra damage with every weapon except the laser) are by far the most useful for combat.
Josh and Stan make for an excellent pair when searching for items. Josh can tell if there are still items in the room that you haven't picked up, letting you know whether or not to keep searching or move on, and while Stan's ability is more situational, him being able to both find pickable locks and pick them faster than the other characters has its uses (especially if a monster is closing in and there's a locked door between you and escape).
Kenny is a lower-tier character, as while his ability to sprint can come in handy for jumping in and out of melee combat, it doesn't bring much to the table if you also have Ashley. Furthermore, sprinting away from combat is a good way to leave your slower partner to his or her demise.
Shannon is probably the least useful, as both of her unique talents (puzzle tips and improved healing with first aid kits) can be accomplished in the hub zone.
The second game:
Anvilicious: From the second game's opening scene, it's shown that the students at Fallcreek only care about two things. Then just in case the player didn't get it, it is then stated outright, through a report in the hospital level, that the infection which consumed everyone on campus was spread due to rampant sex and drug use. To really drive home the point that those are bad things, by the end of the game all the characters that were partying at the beginning have been killed off, mostly in an arbitrary and brutal fashion. In other words, just what you'd expect from a playable teen horror flick.
Contested Sequel: While the Anyone Can Die mentality and minor differences between the characters were enjoyed in the first game, the second game introduced some twists. The scripted deaths, starting with Jun, really turned off a lot of the fans.
Designated Hero: Shannon. She only helps out halfway through the game, and belittles her brother when he is struggling to adapt to the spores. Given that she adapted already, perhaps a little more practical advice could've helped instead of insults.
Ensemble Dark Horse: Corey and Mei ended up being the most popular new characters introduced in the second game. A Google image search for Mei alone brings up a good deal of fan art of her, and Corey himself has a few. It helps because Mei suffers a completely unexpected and brutal death at the hands of Kenny, and poor Corey commits suicide after being infected. Game Informer even listed Corey and Mei #14 in their list of Video Games' Cutest Couples.
Goddamned Bats: The Harpies. They're fast, they attack in groups, and they're almost impossible to hit with melee weapons, forcing you to waste precious ammo to defeat them.
Moral Event Horizon: Former hero Kenny, following his mutation, takes a flying leap over the horizon following a FaceMonster Turn, starting with crushing Mei's head under his heel while her boyfriend Corey watches, then abducting his girlfriend Amy to rape her offscreen.
Nightmare Fuel: The mannequins that appear in the dream sequence of the prologue. And that sound they make when you hit them.
Strangled by the Red String: Shannon and Stan. Granted, there is a Time Skip between the two games, but there is no mention of it previously, and their kiss just comes out of the blue.