Its a very, very Mad World.
Gameplay: Insane. Nearly non-stop action keeps your eyes locked on the screen, looking for the best place for cover, or the best way to flank the Locust scum. The only slightly unpleasant thing is that after a while, you actually get physically tired because of all of action... but i suppose thats quite an achievement in itself.
Graphics: Gorgeous. This game has arguably the best graphics out there for any game right now. From the extremely impressive level design, to the spray and splatter of your enemy's blood, to the nightmarish creature designs, these graphics will blow you away.
Sound: Razor sharp. The music ranges from classical music (which fits the setting surprisingly well) to heavy guitar rifts. The sound effects are... gruesome (thats a good thing). The bullets whizzing by your head, the disturbing yells of your Locust enemies, and the roar of your chainsaw bayonet ripping through the poor bastard you got close enough to use it on, are all stunning.
So, I am amazed by this game. Whoever is reading this, you owe it to yourself as a gamer to at least rent this game.
P.S. Yeah, this game blows Halo away.