The unbalanced gameplay, mostly. It's fun but it's horribly unfair. It's either unfair for me or my enemies.
And it's not like it can be fixed (or that I even want it to be fixed). Things like the Supers are what I mean by unfair, and I do not want those taken out of the game. It's just an opinion of mine to think that I prefer communistic-styled multiplayer.
I agree when I was a level 5 playing in the crucible against level 8s I would get killed in two maybe 3 shots when it took me 6 shots. And then the interceptor was just wrong, but they said they would tone it down so hopefully they get it right this time.