I'm really disliking Thief: The Dark Project so far. Ugliness aside, the stealth is so easy a chimp could master it, the controls and combat are really awkward (For some reason you aren't allowed to walk backwards and I had to bind keys just so I could strafe. :l), they don't do much to establish the lore or the characters so the story feels hollow at this point, the AI is so thick I actually dispatched two of my foes by making them drown themselves. That said, it does have a sort of stupid charm to it, especially the voice acting (of everyone besides the protagonist) and the hilarious animations.
I got literally zero enjoyment out of Operation Flashpoint: Dragon Rising and I still call that just about the worst game I've ever played. Spend half an hour skulking and sneaking, fire one shot and have every man and helicopter on the island riding up your ass within the second. I must be doing something really wrong in that game, because I feel like I wasted two dollars on it.