There are a couple of things that annoy me right off the bat in competitive.
The first being more serious (in my opinion), which is that there is little to no feedback to the player when they land a hit on an enemy, at least not that I've noticed in my sleep deprived stupor over the last 2 hours. Not knowing how many hits I have landed means I have no idea how wounded the enemy is and how long I should concentrate on him or whether I should follow him to finish him off or not. Players also seem to take a hell of a lot of bullets, even to the head but this might just be me.
The second issue is a tad selfish but if I have run the length of the map, carrying the idol in plunder mode, killing anyone that comes near me to take it off me then it really sucks that I have to throw it up into the top of the building just to have someone else pick it up and claim the point/capture. I know the mode is about teamwork but a little recognition for my hard work would be appreciated.
Having said that, not displaying your k/d during plunder mode is a stroke of genius. People might (here's hoping) play more tactfully and work as a team instead of just going after kills. Then again you get money and level up from kills so I am probably just dreaming here.