As much as I've tried to like the ARMA series, I've never quite managed to. Even leaving aside the voice acting (seriously, where do you find people that can emote that little? It has to be some sort of asylum, right?) the controls are just too stodgy to be fun and the enemy has very strange detection AI.
To give just one example, I think (still not entirely sure) that the game models your entire character in the physics engine and prevents clipping with the enviroment, which means that you can't turn around in a doorway or something similar. All well and good, but this is never actually shown. You don't see your gun bumping against the frame (presumably to avoid the question of why you don't just lift it up and turn anyway), your mouse just stops working while you're in a doorway. And (did I mention it was one exampel of each?) enenmy tanks can somehow hear you if you run past them too quickly. Yes hear you. I checked all the cameras with my binoculars (at least the ones I had access to when driving the thing) and they were all pointed away from me, I run past it and it hears me!
And speaking of hearing things as you run, there's a very strange jogging effect in ARMA II. It sounds like two plastic cups knocking against each other in your backpack and is not conductive to stealth, so either nobody thought to wrap your dinner utensils in a bit of cloth or your character has plastic limbs.
I'm not saying that ARMA III will definatly be bad, but this time it'll have to convince me otherwise before I buy it, instead of me paying quite a large amount of money (considering campaign length of the other games) on good faith.