I'm very impressed by the Beta!!
The only thing I'd like to get in the full game is that you should be able to change the controller settings more.
I love the green thumb (german: Grüner Daumen) controlls its very close to any other shooter controlls like cod, bf, .... the thing I would realy like to see is that you can switch RB and LB as an oppurtiunity. The rest of the Beta is very very very nice and it would be extremly nice if we could play it longer or an second wave of Beta should come because I can't wait so long for the full game.
The new game modes are allsow very nice. Breakout is Hot.
Of course little things are not ready in the menu like in spartan-central sometimes models are not loading and I'm pink all the time but I'm sure this will be fixed. Perhaps some more oppurtiunities could be integrated their too like models for legs, arms .... as in Halo 4.