It's probably the biggest insult you can give a game: calling it boring. I mean games are most of all made to entertain, and yet there's some games that are about as exciting as staring at the ceiling on a Monday morning at work.
I've been playing Farcry 2 lately (enjoying Farcry 3 made me interested in giving this game a try), and.... yeah. I mean sometimes even a boring game can have its charms, and I guess the whole mercenary in the Savannah thing got me interested. But, everything about the game is dull: the shooting, story (or lack there of), everything. I spend half the time running from mission to mission, and they're about as intriguing as an MMO fetch quest. I guess the game still has some charm since I've been playing it for about 3 hours now. But it's that dull and boring sense of charm, like listening to really slow and melo music that puts you to sleep.
I really don't think I've ever been more bored with a game. Oblivion comes to mind (at least for me) but I think this game even tops that.