Having played quite a lot of both ArmA and PR, I have to say that they're quite different but brilliant in their own ways. ArmA truly reaches its full potential when played with ACE or other similar mods, and it's a bless that the ArmA community is as productive as it is; without the tonnes of addons, mods, missions et cetera the game would be... empty. Really, the community (and the editor) is the strongest side of the game. The gameplay in ArmA, compared to PR, is more slowpaced and unforgiving. Commanders have to sit back and plan their actions in much deeper detail before moving out. Some missions does not even offer the luxury of respawning, so each friendly casualty hurts a lot more. Its downsides are, however, that controlling infantry is like using a robot; the controls are very clumsy and sluggish, which makes CQC bothersome and frustrating. Oh yeah, you can't jump or climb over walls, either.

Another downside of ArmA is that you pretty much have to play with a clan or a community to get anything out of the game. Playing with pubbies does simply not work properly; there are seldom leaders who can issue orders for everyone on the same team, and if they are there, no-one listens to what they have to say. This leads to a lot of dead players, no cooperation, a lot of confusion, frustration, and on top of that a commander screaming on top of his lungs on the team channel. And let us not forget about the bugs. I've seen tanks being thrown to altitudes of over three hundred meters, people getting stuck inside vehicles, headbobbing from hell, et cetera.

Now PR is a little bit different: When the commanders in a typical mission in ArmA would sit at least five minutes drawing markers, discussing different approaches and fixing squads, it takes about one minute to get everyone organized in PR. You don't have to plan missions days ahead, you just have to join a random server and there will be at least one squad full of people who communicate, follow the commanders orders, and are generally cooperative and fun to play with. Also, CQC as well as medium- to longrange fighting works good in my opinion, although the viewdistance is a tad low for my taste. The infantry controls are smooth and feels much better compared to ArmA, but the vehicles are another story.

Everything stated above have probably been said earlier, but yeah :3