It's not that Halo is a bad game, it is just there are so many people thinking it is more than it is. Like Goldeneye 007 (N64) before it, it took FPS gaming that existed on the PC and successfully brought the experience to consoles. It deserves praise for doing so, but not as much as many of the players gave it.
Now it seems MW2 has taken Halo's place where the twitchy, Ritalin popping, Caffeine addicted, FPS addicts go. It's helpful to be able to tell what kind of gamer a person is just by if he is playing MW2 all the time and nothing else.