Well, not only a few months ago, I was actually looking through PR/ArmA comparison threads like these, trying to see if purchasing ArmA would be worthwhile;
would ArmA be a good game? Lucky for me, my friend purchased me a copy over Steam, so I had to look no further, I could just try out the game.
Now be advised that my experiences with ArmA are playing nothing except ArmA with the
ACE mod (Advanced Combat Environment), which is pretty much the "PR of ArmA". I've no experience in vanilla ArmA, but I've been told that it's probably nothing worth my time now that I've been playing ACE, and that ACE is "the shit".Those of you who are posting negative responses to the game probably played some of the early versions of the vanilla ArmA (which I've heard, sucked... To some extent).
Playing with the TacticalGamer.com community, ArmA with ACEmod was actually fun. There's definately a LARGER learning curve to it than vBF2 and PR combined, and slap on the confusing key controls and you've got yourself one heck of a newbie. I think you have to have more patience when it comes to ArmA, it's definately not a perfect game, but it can be fun at times. ArmA has some of it's little quirks too, like I often dread long briefings and drawn-out plans. Some people love the planning aspect of the game, and some love the execution of the plan. In short, ArmA, gameplay-wise, is a step up from PR, in terms of simulation.
Personally, I play both PR and ArmA, and love the two equally. PR is something that you can jump on and play for an hour or so, and then go do something else. To get the most out of ArmA, you've got to devote some time to it, as well as a little more patience, as installing patches and mods can become more time-consuming than say, PR.
Lastly, I recommend ArmA for those with patience and a desire for simulation a step up from PR. I can compare the two, but they're just really different from each other. (Oh, and if you tried the "demo" of ArmA, it represents nothing of the actual game. The demo is bugged and **** compared to the latest version of ArmA).