No, seriously. A 10. It's a great game. I bought the Xbox 360 for the Halo series.
1-Any rating you give this one, it'll be a good game nevertheless.
1-Like any awesome game, this one has superb graphics.
1-Every voice actor fits their character exactly, and the guns and explosions all sound like they 'should,' even the alien ones.
1-You can choose a variety of difficulties in this game, even though legendary isn't enough for me anymore...
1-You can make your own maps, always a plus.
1-The campaign is just long enough to keep you occupied when you're taking a break from 'pwning noobs.'
1-You recharge health (Aka shields to experienced players) in this game, so the amount you get depends on your strategy. You also respawn in co-op.
1-The grunts are stupid, the jackals are moderately smart, but the brutes, like they should be, are capable of strategy...kinda.
1-Halo has always been bad with glitches, but you always get killed while executing them in multiplayer, so nobody ever gets the upper hand. If you want a REALLY glitchy game, check out Halo 2, it's probably the best glitching game on Earth.
1-OMG, NO SERIOUSLY HALO (The series in general) HAS MY FAVORITE STORY EVER! If all you're looking for is a solid storyline, this is hands down your best bet. I, myself would buy the trilogy and play them in order, because it's much better when you understand it.