While I just registered today, I am certainly not a stranger to OFP (the one and only true Operation Flashpoint: CWC/Resistance) and ArmA I and II. I think a lot of gamers on other forums who are unfamiliar with ArmA, as in those bashing ArmA don't realize both games are very different and therefore shouldn't be compared.
A friend of mine recently bought a copy of DR and I was able to play on a little. My first impressions were remembering the days of the original OFP: CWC and this new game DR were the pace of the game and overall feel.
Although DR does factor in 'critical-hit' dynamics and a command system, it doesn't really have an atmospheric feel to the original OFP or ArmA series. There isn't that same type of immersion I had when playing those games.
Visually it's a nice game to look at, but I really can't say I would associate it with the original one that was released eight years ago. So at least in my opinion I don't consider it a sequel, but a different game entirely. Just my thoughts.