Polished enough to blind you!
Everything is balanced, from the armor abilities to the weapons. Enemy AI is engaging and responsive, while friendly AI still lacks the brain power to fully function in a battle. Vehicles are still easy to learn and difficult to master and the story fits right in to the canon (from what I see playing Halo games alone.)
Graphics are great but I'm not a huge fan of the excessive motion blur; however, they are better than Halo 3's. The game manages to give you the gritty look and feel without sacrificing the bright color palette.
In the end, I would've given the game an 8.5 but I bumped it up for the amazing amount of polish the devs gave Halo since H3. Forge, theater and firefight are things that we've seen before but I attribute any additions made since the previous installment to the general idea of "polish". As I said in the beginning, if you're expecting anything other than Halo, prepare to be disappointed. To the fans however, day one purchase.... I have mine.