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.
And lest we forget, the menu theme for Conviction by none other than Amon Tobin himself.
The 3DS port of Chaos Theory received a mixed reception, but almost everyone agrees that its theme song Breaking Protocol, once again by Amon Tobin, kicks ass.
The first game has "Common Fight" which plays when a suitably epic moment is happening (such as escaping the Kalinatek building, the showdown with Grinko in the abattoir, and the shootout in the Presidential library). Also doubles as an Autobots, Rock Out! song. Unless you were playing the PS2 or Gamecube version of the game, in which case this awesome track was only used once during the escape from Kalinatek.
The entire Double Agent soundtrack, Particularly the Kinshasha, Iceland, and Cozumel fight themes.
The early development shots of Conviction divided the base on whether "Social" Stealth in place of Light/Shadow Stealth. Ubisoft then went and redesigned the game to have use absolutely no Social Stealth and more action than previous titles. This resulted in a new split, between those who think that the action elements are fine, and those that don't.
The decision to recast the voice of Sam (from Michael Ironside to Eric Johnson), and ostensibly make him look younger, alienated some fans during the runup to Blacklist's release.
Complacent Gaming Syndrome: The Five-SeveN pistol in Conviction is the only pistol that most players use because it has a high clip capacity, a built-in silencer, and it's the only gun in the game that can mark four targets. The fact that you find it very early in the game also helps its popularity.
Contested Sequel: Although Convicton was generally well-received, some longtime fans of the franchise didn't like the increased emphasis on action over stealth. With Blacklist Ubisoft has attempted to find a happy balance between the action-oriented gameplay of Conviction and the stealth-oriented gameplay of earlier Splinter Cell titles and for the most part fans and critics alike enjoyed it.
Demonic Spiders: PLA Soldiers in the first game. They can kill you in 3 hits even on normal mode, come in large groups, and some even have flashlights attached to their helmets making hiding in the dark useless against them.
Heavy Infantry in Blacklist, you can't knock them out from the front and you can't gas or shock them, sneaking up on them from behind is risky, taking them out from above or using an execute with the gas function of the crossbow are the most reliable ways of taking them down.
Dogs are fast, hard to hit, and will hold you in place once they get close to you until you can shake them off, making you a easy target for enemy soldiers. They will also smell and follow you even if they can't see you once you come within a certain distance of them, which also alerts enemy soldiers and brings them along with the dog.
Even Better Sequel: Pandora Tomorrow to the original and Chaos Theory to Pandora Tomorrow.
Genius Bonus: Some of the Gone Dark missions in Blacklist have really obscure clues as to where to go next.
Goddamn Bats: Drone operators in Blacklist, they themselves aren't numerous, but until you take them out, they will keep on sending drones and prevent you from using your goggles.
Older Than They Think: Conviction's critically well-received "Mark & Execute" system was pioneered in the Rainbow Six: Vegas series. Which is unsurprising, considering that the games have the same gameplay director.
The Mac version of Conviction unfortunately qualifies as this as well, no thanks to Ubisoft's "Always On" DRM.
The Gamecube and PS2 versions of the first 3 games were horribly gutted in comparison to the Xbox and PC versions, (for the first game, it is so bad that the Splinter Cell wiki refers to it as "Version 1" (Xbox and PC) and "Version 2" (Gamecube and Playstation 2)). Because of their weaker hardware, not only is there Loads and Loads of Loading, but there were also many instances where you fight fewer enemies and some levels were reduced in size compared to the Xbox/PC counterpart. In fact, it is not much of a stretch to say that playing the Gamecube/PS2 version and the Xbox/PC versions feel like playing two different games. The first game especially: because the changes to some levels were so severe, the Gamecube and PS2 versions had to insert several additional full-motion video cutscenes to compensate and try to fill in some plot holes. example A big example is the CIA infiltration mission in the first game: the Gamecube and Playstation versions start you off inside the building instead of having to infiltrate it from the outside in a rainy night. Presumably, their weaker hardware couldn't handle the advanced lighting effects of rain and lightning in an outdoor nighttime setting. As stated earlier, a very flimsy Handwave is given where they had to insert a cutscene with Sam using a fake ID to get in. Another big example is in the final mission of Pandora Tomorrow: you must kill 9 terrorists in the Xbox and PC versions but only 6 in the Gamecube and Playstation versions.
For the first game, on the PS2 side to make up for this, an extra level was added between the Kalinatek and Chinese Embassy missions where Sam investigates a Russian nuclear power plant. This is actually a plot-critical level because it reveals where General Feirong obtained the nuclear material for his missiles. But because the power plant mission is only available in the PS2 version, players of the Xbox, PC, and Gamecube versions will have no idea what Lambert is talking about when he mentions in the second Chinese Embassy mission that he has found the "missing Americium-239."
Dufraisne in Version 1. He patrols with three Elite Mooks around the bomb, has always figured out you are the double agent regardless, and it is nigh-impossible to kill or stun any of them silently beyond waiting for them to all look away or wander into total blackness. And yes, Dufraisne and co. can hear silenced weapons and launched gadgets. Even from several meters away.
Infiltrating the CIA in the first game is a beast, because you can't kill anyone or be seen.
The Abattoir mission ends with Sam finding the hostages, only for Grinko and his mooks to start flooding in; granted, you have a turret to assist against them, but it seems out of place and happends pretty suddenly.
The Sea of Okhotsk level in Double Agent isn't very difficult to complete, but extremely difficult to get a perfect stealth score on. To elaborate: despite starting in a blinding snowstorm in white camo, Sam can barely see five feet ahead; however, the enemy can see you just fine. This is because, as far as the game is concerned, you are running around in broad daylight and fails to factor in the blizzard.
Also the Cruise Ship mission. Even with all the general mission difficulty aside, the end of the mission requires heading through the ship's bridge, which happens to contain 4-6 people (depending on difficulty). Did we mention this section takes place during broad daylight near very large windows and with little cover?
Infiltrating Third Echelon and The Russian Embassy in co-op, for being "insta-fail when detected" levels.
To elaborate, unlike Washington Monument where you only had to tail and eliminate the three spotters, in Third Echelon Sam has to plant C4 on the two transformers, then get to an elevator taking Sam to the reception desk. Although he can go loud after this, he then has to quickly get to the end of a hall before two security gates can come down. Even then, a good portion of this level includes long, dull periods where no enemies are about (hence no risk of detection) and it's just Sam moving about on pipes and ledges. White Box Laboratories is actually worse with the second reason despite not being "no detection."
Price Airfield just because while the opening rendered cutscenes are eventually skippable, the subsequent portion using in-game graphics isn't, and in the case of Price Airfield, it is long. Even when you're finally able to move it's just to smack Grim around, and then you're allowed to exit.
The Iraq level of Conviction. While not difficult if you don't mind lethal gameplay, it feels very out of place with the rest of the game and does nothing to further the story except give us a Friendship Moment between Sam and Vic. Also, that fact that you're playing as a soldier means you lose most of your extra abilities, including Mark and Execute and there are no shadows to hide in.
Abandoned City, especially when going for the Undetected and Non-Lethal bonuses. Towards its end, Commandos enter in groups while you have to hack 4 laptops, and they don't stop spawning until you're done. The very last part of the level has Sam and Briggs knocked down on the ground and forced to gun down multiple waves of commandos and drones without being able to move or revive each other, and there is a glitch where dying and reloading from the checkpoint there can stop spawning enemies after so long, forcing a full mission restart. Pray you didn't bring a sniper rifle.
Swiss Embassy, especially in the later waves. The map is small and linear with few hiding spots, enemies come in huge groups, and the later waves are filled with heavy infantry and dogs, including heavy HV Ts with riot shields. Also, unlike most of Charlie's other missions where you can get a mastery in the first 5 waves with some good combos, it is almost impossible to get a mastery in Swiss Embassy without having to go through at least 10 waves. Good luck going through all 20 waves.
Scrappy Mechanic: Although they might just be a vocal minority, some Splinter Cell fans absolutely hate the Mark and Execute feature added in Conviction, feeling that it makes the game too easy even on the highest difficulty.
Granted, they did have a legitimate reason to replace series mainstay Ironside. The voices are to be done in-scene using the motion capture so as to get a realistic, visceral feel, and Ironside is possibly too old to keep doing that(although he did help train Johnson for the part and gave his blessing). It doesn't stop those who don't like the change, though.
There's also the fact that Sam seems to be bizarrely aging in reverse. Blacklist is the most recent entry in the series yet Sam not only sounds 20 years younger, he looks it too (keep in mind that Sam is a veteran of the first Persian Gulf War who also has a college age daughter).
Win Back the Crowd: The promised Perfectionist difficulty in Blacklist seems to be this as it is a return to classic stealth play, removing melees from the front and the Execute part of Mark & Execute, features from Conviction that may have deterred hardcore fans of the earlier games.