See also:
- Broken Base: One half of the fanbase love the new cartoony style of the game, while the other half dislike it and prefer the more gritty art style of the original game. There are also a lot people who found the gunplay to be very lackluster and not as fun as that in the first game.
- Demonic Spiders:
- Carpet bomber planes during the final boss battle are difficult to hit and even more difficult to avoid.
- Chaingunner zombies are like arachnoids in the first game, but they're much quicker when it comes to firing at you and they do more damage.
- Appropriately enough, Big Spiders. They're big enough and have enough health to qualify as mid-bosses when they appear, spawn regular spiders periodically, and unlike most enemies actually lead their projectiles to hit you.
- Difficulty Spike: First off, if the vehicle you need to destroy The Mental Institution with gets destroyed, you die instantly. Not only that, it can summon planes that either collide with you, carpet bomb you, or just shoot at you as well as launching out cannon balls and big fireballs. The carpet-bombing planes will mess you up if you don't take them out before they let their bombs loose on you.
- Game-Breaker: The Serious Bomb instantly kills everything else within a quarter mile, especially in multiplayer with unlimited ammo.
- Goddamned Bats:
- Flying enemies, most notably Witches (especially Witches, since they move the fastest and can fire and move at the same time,) Floaters, and Harpies. Fatso Fighter and Seagull Bomber planes to some extent too due to being hard to hit but rather easy to avoid.
- Marcel the Clown, an exploding Monster Clown, which can take more damage than your typical Kamikaze and also regularly serpentine towards you to make it harder to hit them.
- Rollerballs are Werebulls in spherical form. They can be knocked back with weapons with high stopping power like the Rocket Launcher or Double Shotgun, but have a ton of health and don't toss you aside when they hit you like the Werebulls do, making it easy for them to surround you and mob you to death if they come in large numbers.
- Most Wonderful Sound: "EXTRA LIFE!"
Best thing to come out of the game. - Narm: Some cutscenes have the potential to be funny (i.e. the Zixie chieftain proclaiming that Mental will never find his Hidden Elf Village while a Harrier jet is literally right outside his window staring at him), but are ruined by incredibly stiff cutscene animations and an awkward script.
- Padding: Just before the first boss fight. They couldn't have been more blatant about it if they tried!"Before you enter the Ceremonial Arena, grab four bananas for good luck."
- Porting Disaster: The Xbox version suffers from considerably downgraded visuals, a poor framerate, and is missing the final boss, so the game just abruptly ends after you get to the end of the final level. Quite disappointing compared to the first game's Xbox port, which was a Polished Port.
- Scrappy Mechanic: A problem carried over from the Xbox port of the first game. Sam automatically picks up... well, pick-ups, even if he's completely full in whatever the pick-up is supposed to fill, making it really easy to waste health and ammo. This was fixed in the Steam release's v2.90 update.
- So Okay, It's Average: The game is generally regarded as this for not living up to the spirit of the first and second encounters.
- That One Boss: Some bosses right after Kwongo may count as this:
- ZumZum is fairly difficult, as you will have to destroy the flowers on each side of the area first before you can actually kill him. But then, it gets worse; it will spawn miniature clones of himself in order to distract/flank the player while being mowed down.
- Prince Chan has a huge amount of health, so you can't kill it with convenient weapons. The good news is that you can damage it by firing the gong in order to take it down. Unfortunately, you'll need to be careful with hordes of nearby enemies that will rush towards you. As long his health is low enough, Prince Chan will walk towards and attempt to slap at you as long you're trying to shoot the damned gong.
- Mental Institution, and it doesn't help that the player comes from the rest of the level, whose enemy numbers put "The Grand Cathedral" of Serious Sam: The Second Encounter to shame. For starters, it's an Advancing Boss of Doom, if you let it reach you, it's Game Over. Also you can't exit from your vehicle, if it blows up, time to reload a savegame. It also can't be damaged directly, it needs to be shot exactly at its core, while it spawns homing kamikaze and bomber planes.
- What Do You Mean, It's for Kids?: The game was given the age rating of 12 in the UK.
