What we expected, and nothing more. Fortunately, what we expected is the best there is.
Graphically, the game is a mixture of good and "OMFG, that is F***ing Amazing!" The textures are iffy, the geometry is okay, and the framerate does occasionally, but...JUST LOOK AT THE WATER!!! That aside, the game also has the best HDR lighting seen in a videogame and the best H.U.D. so far.
To the untrained Ear, Halo 3 will sound like Halo 2. It doesn't when you listen for the subtle changes, such as echoes. The number of sounds for each weapon is rediculous, and that is a good thing.
Gameplay-wise, this is the best system thus far released. Near constant action, combined with smart gameplay, makes Halo 3 perfect from beginning to end. So what if one level sucks? The only reason it sucks is because that one particular level is so frustratingly out of place in Halo 3's style of gameplay. Oh, and play on legendary. Normal is too easy, while Heroic feels somewhat cheap alone. On that note, play with friends. That's how Halo 3 should be experienced: 4 players on Legendary.
What really makes this game great is the amount of stuff to do. Play this game on legendary (with friends!!!), play 20 hours of multiplayer, and figure out the forge, and then tell me that you didn't just have a blast for roughly 40 hours. I won't believe you.
Halo 3 is the logical evolution of the Halo franchise. It won't bring peace on Earth, It is not a radical departure from the franchise in any way, it doesn't shatter minds on any one point, but the sheer volume of awesomeness WILL blow your mind. YOU WILL LOVE THIS GAME!!!