I love the idea of ArmA having a systematic approach on the Menu UI, everything looks quite clean and simple and fits to the Simulation aspect of this game. Though Zeus and Bootcamp introduced new ways of sharing information via new icons and a different approach on interface design in general. In-game UI assets look way more polished than those in the Main Menu.

Random Suggestions:
Overhauled look of Main Menu Navigation (placement and proportion are fine, but the plain texture feels like navigating through some piece of software rather than a game.)

Implement personal statistics for Singleplayer and Multiplayer like favorite weapon, Objectives passed and similar (would work with SP Scenarios and MP Servers that don't allow to alter the actual performance of a player e.g via scripts maybe a mission parameter that disables common eventhandlers and scripting commands like 'this allowDamage false' for playable units)