The red dot IMO is good for medium range battles, in case you want to be sure about your shot. I just hate the fact that in this game, just because your sight is over an enemy, doesn't mean your bullet travels in that direction. That's probably the only thing I miss about MW2.
I don't use the GL that much. I'd rather use the smoke grenade to get some cover, especially on rush maps.
I don't use the guided missile either. It is convenient at times, but I'd rather tag a vehicle w/ the tracer dart. Then I just hide behind cover and my RPGs become javelins. This is because you can lock into vehicles even if you are facing a wall - just fire upwards once you're locked in.