The Halo 4 soundtrack sample is two different Halo 4 music tracks mixed together.
In my opinion the sample track sounds great and still sounds like Halo. I really like the main part and the ending is suspenseful and creepy. I think 343 are on the right track for the sound of Halo.
I would be lying if I said it sounds like Halo. This far I have only heard one song that really has the Halo sound we have heard for ten years. But the lack of that sound isn’t necessarily a bad thing. The soundtrack sample is still good even though it doesn’t exactly sound like Halo. But I do hope we get to hear a few more bit familiar sounds in the game.