It's trying to be too over-the-top. It just looks stupid.
Even most Western shooters suffer from this problem nowadays although to a less extent.
Crysis 2, Killzone, MW, Gears of Wat and the new Medal of Honor too, they all try it too much. It's all about being badass. So many explosions, slow-mo moments, shaky-cam, switching camera angles bla bla... it bores me.
Halo Reach is holding back some of the exaggerated action and saving it for their climax points in a much better way (but sadly I'm not really hyped for it anyway).
I'm starting to really dislike shooters. The odd exceptions are the slow, atmospheric and laid-back ones like S.T.A.L.K.E.R., Bioshock and Half-Life. That's how it should be.