I just hope for improved animations/weapon animations. Atelast weapon animations and how the hands move and muzzle effect.
I've been reading the official forums. The animations are better. The muzzle effect is a single texture. They dont even rotate the muzzle flash between shots. It's BIS...
The engine sucks. No MSAA. Only option is a "fillrate optimizer" that changes the size of the rendertarget, can be moved down to 50% (bilinear upscale FTW) and up to 200% (4 times number of pixels). A developer called that "high quality SSAA", yeah right, the (bad) quality of OGSSAA with the performace hit of 4xSSAA (or worse, because it's evading the dedicated AA hardware, sigh).
Camera based motion blur, some people get sea sick, kegetys already posted a mod to disable that. Excessive amount of post processing that cant be disabled, only toned down, kegetys' mod can disable that, too.
AI has improved, not that it was difficult to improve (I own and sometimes play Arma1 online, with humans). The AI used to stand in formation and ignore the other 6 members of their squad getting bullets in the face. Push the AI up and they would snipe your left eye from 2km away, with a pistol, rusty, from 1940, on the first shot. They would get stuck and generally suck horribly.
Im waiting for amazon to ship me Arma2 soon. Also, the level of fanpersons in the official forums is unbearable.
The game is mostly compatible with all Arma1 mods, porting should be very easy. Some additions (modules) have been made to the editor/system, mod makers seem very happy.
As usual, wait for BIS to fix the engine (only took them literally 14 patches for Arma1 to not suck performance wise) and then wait for the community to fix the game (ACE2 is coming, fuck yes!).