Like what though? My issue has always been that they listen to the wrong people.
From the top of my head: utilizing newer hardware and better performance, included melee, better animation system, better interaction system, better sound design, dynamic lights with dynamic shadows, wet textures and materials, AI capable of going and fighting indoors, pointing, better implementation of scopes a.k.a. "real scopes", distant shadows, better hit reactions, in-game management of addons without need to turn off the game, decorated interiors, bit more environmental destruction, zeroing visible in-game, seamless getting in and out of vehicles, vegetation moving even in distance, rivers and streams, less vanilla look of assets, better driving, proto armor implementation, bigger weapons properly obstructing environment/indoors and thus being unusable, smoke collision with objects and terrain.
Some of those are not properly implemented (destruction of furniture is in but its disabled by default, armor acts weird) yet, some are implemented poorly (like smoke collision) but what is there now is very solid. That plus no simulation bubble and it's a dream come true for long-time Arma players. It's basically everything they wanted. Yes, many features I am missing but this is again very solid foundation. I know that my former unit is going crazy over this and for example guys from RHS are already developing for it because of all the possibilities.
What wrong people did they listen to? I am not getting the feeling that they do.
It's kinda funny situation if you think about it, Arma (3) is ageless, you implement some proper features like this, which were not possible anymore for RV engine and bam, you add another 10 years to its active life. It's that simple. Distant shadows and dynamic shadows from multiple sources is already total game changer. Every feature added to the game is magnified by the fact game is totally open, so shooting from vehicles applies to players as well as AI etc.
There are still many question marks as to what will it be like with lot of people and vehicles, how will helicopters behave, how will mirrors and other be implemented. Time will tell.