Very. It’s mandatory in my playthroughs to have a Monk and a Ninja in my party at all times, both of whom are ridiculously overpowered. If the Ninja can’t win that fight, the Monk can usually finish it. And the Wiegraf fight is certainly easy, but only if you know the trick. I’ve never dared try the fight without the trick; when I play FFT, it’s because I want to play something horribly unbalanced and unfair in my favor. 
Respawning Enemies are my pet hate. (I’m looking at you, FarCry 2). Also, “Race” missions in any GTA game, Escort Missions, and “Fetch & Carry” missions for people who just seem too damn lazy to go and get it themselves.
I like the turret minigame in KOTOR - it’s a nice callback to the first movie, and suits the events of the game. If the badguys are going to take the initiative and attack you while you’re in space, why wouldn’t you have to fight them off with the turret?
I like respawning enemies - in RPGs and GTA-clones they are more or less essential to keep things interesting if you want to return to an area. And they’re one of the big reasons that System Shock 2 is so fun. If you could clear an area, then you’d lose the paranoia that makes you hide in a corner with an assault rifle aimed at the door any time you need to check your map.
Dynasty Warriors 3
Areas with way too many archers (without Musou Armor, that translates to a lot of time spazzing in one place) and officers that are way, way too hard to kill. Also, unless you get a special cutscene (and you have to be REALLY lucky), there’s no good way to deal with Lu Bu other than the obvious, which is kinda hard without, er, “help”.
Dynasty Warriors 4
There are all kinds of places where if you don’t do the exact right thing, you’re either taking endless catastrophic morale hits or losing the stage outright. The absolute worst of the worst are Shi Ting and the Nanman Campaign; Chang Ban (Wei), Luo Castle, and Fan Castle are nearly as bad, and you definitely need to be on the money at Yi Ling as Wu. No wonder Omega Force did away with these “trap stages” entirely after this game.
Dynasty Warriors 5 Empires
It’s frustrating how hard some really great policies are to get (especially with all kinds of worthless policies popping up endlessly). And while assigning officers to specific territories is a nice strategic touch, it can get tedious when your land gets big. I think streamlining this a bit…having a “front” where you put battle-ready officers and an “away” where you keep the reserve…would’ve been a good idea.
Wangan Midnight Maximum Tune 2
I know this is supposed to be the toughest street racing venue in the world, but some of the stages just pour it on way too much. I’m talking “look at their rear bumper from 200m out all the way” painful. In particular, 40, 45, 50, 59, 75, and 79 will have you shovelling in tokens so hard and so fast, you’ll curse the arcade for not switching to a card system like it should have years ago.
Ready 2 Rumble Boxing
Getting through the later matches with Nat Daddy. Like trying to knock down a brick wall with a mattress.
In The Groove
Mines. Don’t like them as part of a regular stepchart, don’t like them all over the place in the stepchart, and don’t like that they affect the score. (Okay as an option or for special modes, though.)