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.
YMMV: Mass Effect 1
Anti-Climax Boss: Husk-Saren is pretty easy for a final boss. Bring a biotic character, even just one, with a maxed-out Lift and just have them use it so you can chip his health away while he's helplessly floating in the air. And due to the fact that there's a cutscene after you get his health, by the time it's over Lift should be finished recharging, which means you can repeat the process again, thus winning the fight without even taking a single hit. Without biotics (which are overpowered in general), however, it is an appropriately epic final battle.
Awesome Music: "M4 Part II" by Faunts, which plays over the credits.
Geth snipers can kill Shepard in one hit on most difficulties, and, if you don't take them out quick, they will. Geth ghosts can be even worse, as they hop around and never stay still and use the exact same weapon.
Ensemble Darkhorse: Nihlus is surprisingly well-represented in discussions and fanworks, including mentions in subsequent games (in contrast, Jenkins is only brought up once) considering what a short-lived character he was.
Evil Is Cool: Saren Arterius from the first game is a well-liked villain for his badassery, intelligence, and cool voice. His master, Sovereign, is also widely regarded as Creepy Awesome.
Any biotic power or weapons talent can become a game breaker in the first game if maxed out. With the right build and the right specialization, Shepard can become a terrifying monster. Adept Shepard with a maxed-out Nemesis class can launch enemies across entire rooms and a dozen enemies in a building-sized Singularity field. That's not counting some of the other powerful abilities, such as Shock Trooper dramatically reducing the recharge time on Adrenaline Burst, Medic allowing you to revive squadmates with medi-gel, and so on. This led to them becoming more balanced in the second game. In Mass Effect 2, biotic powers (with the exceptions of Warp and Reave, which are direct-damage powers that have no kinetic effects) no longer work on enemies who have a form of protection. All ability cooldowns have also been unified (when a character uses one of their abilities, all their abilities are unusable until said ability's cooldown period has finished). This led some fans to complain that this puts biotic classes like the Vanguard and Adept at a major disadvantage on Insanity. The Lift powers alone turn enemies into pinatas.
A maxed Lift alone bears mentioning because it works on everything. Yes, that includes Geth Armatures and Colossi. There's something indescribably hilarious about watching a twelve-foot-tall, ten-ton robotic artillery platform drifting helplessly skyward as you riddle it with assault-rifle slugs.
Maxed Immunity will make Shepard nearly invincible. And with the Shock Trooper specialization, Shepard will be able to reactivate it before it even deactivates.
The Spectre Master Gear weapons when upgraded with good upgrades make cover and stopping firing to dissipate heat completely obsolete.
The Infiltrator is just as indestructible as a Soldier and with the bonus power of AI hacking (available only on a New Game+) can do everything an Engineer can. Their class ability allows them to avoid nearly all problems with weapons overheating and put the most powerful mods on without drawbacks. Equip a Spectre Pistol this way and turn on Marksmanship - they the do the highest damage-per-second in the game.
Artificial Stupidity can happen in the planets you drop on and traverse with the Mako. Enemies can be so far away from you that putting your crosshair over them doesn't cause their name and health bar to pop up (which is possible pretty much all the time on said planets outdoors). If shot at from those ranges, they will fire back, but with expectedly ineffective accuracy, and never go toward you. Use a sniper rifle, attack any snipers they have first, and then you have all the time in the world to take out everything else with no chance of getting killed aside from maybe occasional rockets fired at you that can be easily seen and dodged by moving a bit to one side at such a range. Even Geth Armatures are only a matter of time, the same counter from the rockets applying to the energy balls they fire.
Gameplay Derailment: Ridiculously easy to pull off by taking advantage of a side mission that allows you to sell items for higher prices to a particular NPC. Then you can head to a different merchant and buy them back at the prices you originally would've gotten for them there, and pocket the rest. It's possible to unlock some very powerful weapons and have enough money to buy superior equipment for everyone before even leaving the Citadel. Not quite a Game Breaker, but it does help.
Genius Bonus: Binary Helix is working on a biological weapon for Saren based on a pesticide. Making it Saren Gas. Oy.
Good Bad Bug: There are also a couple of occasions to completely max out your Paragon/Renegade scores in a couple of minutes; however, doing so corrupts your save files, and makes your actual decision in that scenario discounted in the sequel.
Harsher in Hindsight: Tali trying to defend herself when Shepard asks if the geth deserved to be killed in the Morning War makes her justification in very bad taste once you learn about what really happened in Mass Effect 3. When you go inside the Geth Conscious you learn that the geth never acted out of hatred but out of self-preservation. You also find that many Quarian Geth-sympathizers were killed for refusing to kill the geth and their paranoia was eerily similar to Tali's.
Tali: "We made a mistake when we created the geth in the first place. But we didn't make a mistake when we went to war against them. If we had not acted, they would have wiped us out!"
Tali: "The geth are not innocent victims in all this. They're the enemy. They want to destroy us. Not just the quarians — all organic life."
Another one regarding Tali: She was initially supposed to see Fist, a Shadow Broker agent, to give the recording of Saren and Benezia to the Broker. Fist betrayed the Broker and was ordered by Saren to kill her. That could have been the extent of that arc; however, the Broker had ordered Fist to kill her as well. The only reason Tali survived that ordeal is because of Shepard.
Shepard, after abandoning either Kaidan or Ashley on Virmire, says that there is no "right choice" in that kind of situation, and s/he hopes she'll never have to make that decision again. Oh Shep, if only you knew. Just wait until Mass Effect 3, when you're making that same decision only this time it's between entire species.
Hell Is That Noise: The sounds the husks make are frightening, especially as is often difficult to tell where they're coming from.
BioWare and Edge of Reality stated that "Pinnacle Station" wasn't included in the PS3 port due to the source files being corrupted. Even the game seems to have rebelled against That One Sidequest.
The day after Mass Effect 2 was anounced to be receiving a PS3 port, Microsoft released a statement symbollically beating their chests by reminding everyone that the first game, and all of the choices that carry to the sequel, was not doing the same & thus, the Xbox 360 was the only place to enjoy the full Mass Effect experience. Come November 2012, and the original game was released on PS3, thankfully by itself on the PSN Store as well as part of the Trilogy collection.
In a conversation with Ashley, we get this:
Shepard: I don't think kissing turians will be necessary, Williams.
Pretty black humour, but when you find Dr. Saleon, the geneticist who clones and harvests organs from living subjects, Garrus says "I'd harvest your organs, but we haven't got time." This same idea comes back later with Garrus's love of inflicting Hoist by His Own Petard and Karmic Death as Archangel in Mass Effect 2.
Ho Yay: Since much of the dialogue Shepard had was originally meant to be potentially romantic before it was cut, there's a lot of this with Kaidan. It is made canon in ME3.
The NPC combat taunts:"ENEMIES EVERYWHERE!" "GO GO GO!" "I WILL DESTROY YOU!" "TAKE COVER!""YOU MUST DIE!" Did we mention the computer likes to use one of these three taunts every 2 seconds or so? Enemy krogan shout "Look out!" every other second as well.
Most Wonderful Sound: The level-up sound is awesome enough to make the arduous task of killing enemies like Geth Colossi or Thresher Maws worth it, especially trying to kill them on foot instead of aboard the Mako.
Never Live Itdown/Hate Dumb: The most common reason brought up by people who dislike Kaidan Alenko is that he supposedly keeps whining about his headaches. In reality, it is only brought up once by him (and also just once by Dr Chakwas), and he doesn't even complain, he just mentions it.
The krogan battlemaster on Therum, at least if you go there early. Some classes may find the fight easier, however, such as the Soldier.
Matriarch Benezia, mostly because of the asari commandos and geth snipers that help her...and because this is often not only one of the hardest fights in the game, but also the most prone to glitches, making it a Luck-Based Mission for many (if Benezia decides to start throwing magically cover-ignoring Warps at you, you're done).
Those who don't completely hate the Mako still admit scaling mountains are no fun to traverse in a vehicle ill-suited to do so. Pray that the planet you land on isn't 80% mountain. Similarly, any planet where you can fall into a ravine surrounded on all sides by cliff faces, forcing you to return to the Normandy to get decent traction again.
The game was bad with these. They can all be described the same way: Even players who have played multiple times lose track of them all, and it is kind of a pain running around and collect them. Included are:
Finding all the keepers on the Citadel.
Finding all the Resources.
Finding all the Matriarch's writings.
Finding all the turian symbols.
Finding all the salarian League of One members.
The Volcano Hunt mission in Pinnacle Station. You get more time on the clock for each enemy you kill, but the amount of time you get back is progressively less for each one. You will want to put your keyboard/controller through the screen after coming up 2 kills short of the top score for the 10th time. For some reason, the Volcano map is the only one with this problem - with the others, a sufficiently skilled player can keep the mission going indefinitely and have no problem racking up enough kills.
The rogue VI assignment on Luna. You have to clear three bases full of hovering drones that can kill you in one hit. And the shields it throws up over the consoles and doorways. It's meant to be a disturbing, desperate last means of defending itself, but just becomes tedious. The class specialization choice you get as a reward almost makes up for it, though.
Too Cool to Live: Nihlus is a hardboiled Spectre built up as a badass as well a potential mentor, and he dies very quickly to establish what kind of guy Saren is.
He gets a decent back-story in Mass Effect 2, if you talk to Samara. Apparently Nihlus was so badass that he was able to stop her from killing him simply by using her own justicar code against her and allowing him to escape.