Having played Dragon Rising (the Flashpoint before this) I can honestly say, Operation Flashpoint games are the second furthest shooter from a MW clone you could possibly have. OF is a super realistic shooter, not boring one man army CoD style shooter. You get shot, even in the leg, by a pistol, and you better patch it up before you bleed to death. All weapons have bullet drop, etc...
It's realistic.
So if you're comparing shooters Operation Flashpoint = ArmA II =/= CoD/BF/MoH
If that's your style go for it, if not, don't. Personally, I'll stick with ArmA II and Dragon Rising for that style shooter. But it's really nothing at all like MW.