The current spectator mode in Arma 3 (specifically the free camera mode) is in my opinion sluggish and unintuitive to control. This is particularly noticeable after using the Zeus interface.
I propose that if possible make the free camera spectator mode basically a stripped down Zeus interface without any of the editing options. This would reduce the number of control schemes players have to memorise and get used to and i think overall improve the spectating experience with the quick and responsive camera movement that the Zeus interface offers.
(Note: The chase camera and the first person spectate mode work fine in my opinion. If it were possible to do the above changes and preserve these features at the same time that would be ideal.)