The stun effect was great, I never read or saw anything that said why they took it away. Perhaps they felt it unbalanced the game outside of campaign.... who knows. WHY, BUNGIE?

The plasma rifle actually looks alien compared to the repeater IMO. It's not as bad as the storm rifle though.

I never liked the whole analogous armory between the factions (BR = Carbine = light rifle, for example).

The alien weapons don't feel alien at all in most cases.