Like most, I loved Oblivion when it came out. But man, those oblivion gates. What were they thinking?! Sure, it's pretty sweet being known as the "Hero of Krevice" for the rest of the game, but having an oblivion gate pop up every 30 feet gets to be a chore. Also, think that game had level scaling.
Also, every game I've ever played has that one level/dungeon/quest that is required that I can't. fucking. stand. This usually pulls me out of the game.
In BG2, it's the starting in BG - hate the initial quests, but the game gets better after that. Have to grit my teeth past the illusionist quest, and a lot of shit.
In Arcanum, it's the Black Mountain Clan, but whatever, I just take harm and kite, but that dungeon goes on forever...
In Wizardry 7, it's Munkharama
In GTA:SA it's Stealing from Uncle Sam - where you have to just load boxes onto a truck, but you have to do six and its a slog
M&M VII - what, it's the Dwarven Mound with the XI, V, III type doors. Just brutal. Let me get back to Arcomage, get me out of here.
In Morrowind... eh, I like all the quests in Morrowind. Fuck, that whole Dweomer Puzzle Box or whatever quest that you get right away in the game, that really caught my attention. That was a GREAT quest, as well as just finding Casius there.