Thief 2.
-It's so good it made all other stealth games that weren't in the Thief series utterly unplayable to me?
-Oh, I have a real complaint actually! Your character seems to be wearing wooden clogs while trying to sneak. One step on a marble or tile floor is somehow louder than a man screaming in pain as you shoot him with your bow...
Morrowind:
-Medium armor is horrible. At least it looks good though.
-CLIFF RACERS
-You can't control your blocking, and attacks miss
-For the first 6 levels you move slower than a snail weighted down with lead.
-Pickpocketing is completely pointless.
-I always run into an annoying alchemy bug that makes it so I can't brew potions.
-Poisons are completely useless except to sell
Deus Ex:
-The sword you pick up in Hong Kong is amazingly overpowered.
-The poison darts ARE NOT STEALTHY.
-There are a lot of bugs involving stealth, like enemies will magically know you killed someone in a room they could not see
Some people would complain about the graphics...But I refuse to. First, these games are old. Deal with it. Second, I play games for gameplay, I'll look around at real life if I want great resolution. Third, the dated graphics make these games playable on my junk laptop.