A list of some of the gameplay sequences I find annoying. Funnily enough, a lot of them seem to be in Mass Effect 3.
1. Hades Cannon. I DESPISE THE GROUND SHAKE!
2. The ambush sequence of the Citadel DLC. Because the fake Supressor kills your cooldowns and playstyle, and tacked-on terrible stealth missions in games not built around stealth always suck and eventually you cannot stealth anyway and oh how I hate this section so much.
3. Marauder Shields and the Three Husketeers. The game is actively fighting your aiming. Not sure how bad this is on PC with a mouse to aim, but it is extremely frustrating on console. I have the Insanity achievement, so I just drop the difficulty to Casual at this part so I do not waste a lot of my time.
4. The last 10 - 15 minutes of Mass Effect 3 because I cannot skip through the dialogue and I just want to finish it already.
5. Two Turians outside of Chora's Den in Mass Effect 1 with a low-level Shepard.
6. Antibaar(?), one of the Geth outposts in Mass Effect 1. If you want the as much XP as possible, you need to kill outside of the Mako and it can be difficult without a sniper rifle. Even in the Mako, you can take too much damage and have to wait a looooooooong time to get its shields back.
7. Arrival DLC. I both like and hate this DLC. Fighting solo can be fun. It can also suck. I tend to like/hate it on different playthroughs.