ArmA's graphics were subpar at best. The movement was retardedly slow and if I recall, the whole vehicle system just sucked. In addition one of it's biggest draws was the high player count, but I never got above BF2 numbers without it lagging so horribly bad you couldn't play it.
I also have yet to play a game that IMO really captured the effects of recoil realistically. ArmA was yet another good idea, bad implementation game in my book.