i used it alot when i was using the brits crocs so i could burn the 88 crew out (witch worked great) but when i figured out that the marders Still hit when they fire trough smoke or when my tanks are in smoke i lost the intrest in using it as an defencive weapon but it still works great against paks and inf and i recomend you try using it that way.
it's a great defensive weapon, i've screened not only my vehicles but my teammates vehicles from being taken down several times, i even saved a vet 2 pershing with it while crippled.
with B HQ you get it on cooldown, then it really shines, use it for infantry assaults, retreats, for hmgs, etc, i love it.