Accidental Asari sex
What was wrong: Haha, oh man, what wasn't wrong with this?
Sha'ira, aka "The Consort", is best described as an Asari who watched a lot of Firefly and decided to hang out on the Citadel and base her life on Morena Baccarin's character.
If you complete a quest for her, she gives Shepard a key and some fortune-cookie advice. If you respond with "That's it?" as a dialogue option, you're treated to a fairly G-rated sex scene.
Dude, we're new to being Shepard! FemShep hasn't even decided if she swings that way yet. Plus, considering the Asari might brainwash other races to find them attractive, it raises some serious issues of consent.
Above: Advisor. Companion. Sexual predator
What was right: Snickering at a new player saying "Wait, what?" as they accidentally stumble into interspecies nookie.
What we don't miss
Not every feature of Mass Effect 1 had some redeeming quality. Good riddance to these.
The hacking minigame: Pressing five buttons in a row is an OK abstraction of some technical task, but you had to do this minigame to accomplish even the simplest tasks. Opening a locker? Hacking minigame. Dropping a beacon by some rocks? Hacking minigame. Pulling a dog tag off a corpse? Hacking minigame. Blatant discrimination against the fat-fingered and/or drunk.
Long missions, sparse autosaves: The three big plot missions of ME1 take a long time to complete compared the bite-sized chunks of the sequel. If they didn't feel like a slog at first, they did once you got killed by a stray rocket and discovered your last save was from 45 minutes ago.
Prefab shelters: From a story perspective, it makes sense why you'd keep encountering the same three structures over and over again. What's an interplanetary settler going to build a custom house out of on some deserted planet, rocks and other rocks? Heck no, they buy manufactured housing! And then strew the living areas with irregularly-sized crates to function as convenient cover.
Thankfully, ME2 was willing to bend believability a little, and gave us varied and interesting environments on side missions.
Space racism: For a bunch of human supremacists, Cerberus is remarkably chill about aliens hanging out on the Normandy. That's good, because the aliens were the most likable characters in both games, and the first crew's wariness didn't make them particularly sympathetic.
Above: Oh, you say you're suspicious of letting Garrus on the ship? Hope you weren't real committed to surviving Virmire, lady
Limited voice samples: Modern video game enemies make it a point to announce what they're doing to everyone in earshot. Usually, that works pretty well. Enemies in Mass Effect 1, however, mostly wanted you to know that they will destroy you, and that it is time to go, go, go!
Elevators: Much ink has been spilled over the infamous elevators, and there's no need to belabor the point. These are the only thing in gaming that has ever made us long for a load screen.