Modern Warfare 2, in my opinion, it was horrifically handled for several reasons;
1) Campaign lacks the same immersion; sure it looks pretty, but I really disliked the plot; it lacked the plot twists of CoD4 (come on, Shepard was way too obvious; he looks and sounds evil) and skipped around too much.
2) Multiplayer was as unbalanced.
3) Spec Ops was really badly handled; there was a lot of potential in it, but they copy-pasted far too many maps. Plus it could have easily been 4-player.
4) Most of my other reasons can be found here, in this rather humorous video -
<youtube=98IllinIqe8>
Edit: Also every Pokemon game since the series moved onto the DS: I don't know why, but they just don't feel right anymore, plus I hate the DS's shape because it makes my hands stiff.