Ok. so the OFDR is not as detailed (realism-wise) as Arma2 and it may not have as detailed graphics and terrain and what not. So what?
Speaking of visuals, I think people are a bit too harsh on DR, I actually love the grass and sort of a cinematic feeling of the whole enviroment. While Arma feels a bit 'weathered' in that regard, colors in OF

R are more refreshing, to me even cartoon-like (which I actually like..so sue me

).
What I miss in OFDR is seeing my own soldier's body/legs and little things like slow 'patrol' walk etc. Not being able to look around (free look) is also somewhat problematic IF you're into Arma and the walking animations are a bit..funny.
But, I do love the explosions and weapons, especially the grenade launcher. Tanks and vehicles are also nice, bouncing off trees is a letdown but hey..don't hit the trees and your Abraams will be just fine!
The AI to me, seems really good and ballanced between sniper-accuracy and human-like behaviour. In fact, it seems to me AI in OFDR is somewhat more refined then in Arma as I'm yet to see it do some weird things like turning back to a tank or simply running in the wrong direction while being under fire.
Sure, if I really want to immerse myself to as realistic as possible mil/infrantry experience I'll fire up Arma but sometimes I kinda get tired of it and that's when I go for OFDR, I call it Arma light (no pun intended!) and I think it's good CM opted for a game that would hover in between BF2 and Arma2 worlds, it's a refreshing approach and I'm sure it will attract more people to it, who are not too crazy about ultra-realism but also do not want a totally arcade game which makes no sense and in OFDR you definetelly have to think and use your tactics!
I also love the mission editor and how easy it is to create a quick combat scenario, even without tutorials.
Overall, I really like OFDR, it's a great game and once all the hype and expectations settle down, people will realise this game is so fun for what it is - a mainstream tactical shooter.
So, if I had to grade it, 1 to 10, I'd give this game a solid 8!