All I'm hearing OP is excuses for why you're not very good at the beta but are used to playing well in the other Halo games. I suggest you read the following site:
http://www.spiritus-temporis.com/scrub-gaming-/
You'll not be the only one who is whining iver the changes though, it happened with Gears 2 when I had to listen to people bitch for 6 months that they no longer had a ridiculously over powered shotgun.