I've heard it was supposed to be class-based, is this true?
We don't know. That trailer is about all we get. I keep hearing rumors about it either being class-based or squad-based, something to stand against the traditional "rambo FPS" aspect of the other Halo games.
If you haven' noticed. The only Halo game with changed gameplay was an RTS and sucked. Still over hyped I see
That wasn't made by Bungie, it was made by Ensemble, and the cutscenes in that game were probably some of the best cutscenes I've ever seen in my entire life. They were movie theater quality. The game itself, however, was mediocre. As for "over-hype", that's all fan hype. Bungie just released a trailer, they didn't go around saying it was the best thing since sliced bread (see: Prototype).