I haven't been playing Quarantine that much, and never saw the flamethrower in action until last night when a guy used it in Fire Team. I wasn't that impressed (then again, this was against human bots, not infected players (sorry, can't call them zombies - I'm a Romero snob).
I need to add that this guy was among the first players dead. Meanwhile, other low-ranked guys with M16A3's holding their own with those of us using "better" weapons. It just goes to show you that money (NX) can't buy skill.
(And NO, I'm not saying that I kick @$$ any more than anyone else).