German soldiers in WWI with flammenwerfer
Flamethrowers have a large number of advantages as a weapon. First off, they would be absolutely terrifying to face. They have also shown an ability to kill or injure troops that are in positions that give them high amounts of protection from bullets and bombs like trenches and bunkers. For example, in the Pacific Theater, US Marines reported that Japanese troops hiding in deep cave complexes were suffocated when the flamethrowers consumed all the available oxygen. Range of most flamethrowers is really pretty good, about 70 feet for an effective range, with maximum reach of about 130 feet. This is good, but well within the "easy shot" range of any rifle.
So as we can see there are significant disadvantages to using a flamethrower. First off, the weight. The full system weighs almost 70 pounds and that is only enough to have a few seconds of flame. Also, being the only guy in sight who is controlling a 100 foot long flame tends to get one noticed. And shot at. The Soviets attempted to camouflage their flamethrowers to lessen to risk of the operators being singled out and killed. Despite what we see in the movies, they weren't quite as likely to blow up if damaged or shot, but if given a choice I would certainly be happy for some other guy to carry it.
And he can stand way over there.
Model: M2 Flamethrower
Feed System: nitrogen(Propellant) and gasoline (fuel)
Weight Unloaded: 48 lbs (68 lbs filled)
Cartridge Capacity: 2 (2 gallon gas tanks) 1 nitrogen tank
Manufacturer: US Army Chemical Warfare Service
Year Produced: 1940-41
Military Use: Flamethrowers would project a stream of flammable liquid, rather than flame, which allows bouncing the stream off walls and ceilings to project the fire into blind and unseen spaces, such as inside bunkers, pill boxes and other protected fortifications during WWII. The flamethrower had great psychological impact on a German emplacement.
The Department of Defense decided to discontinue all use of flamethrowers in the arsenal in 1978. The overall effectiveness of the system was called into question, especially in light of the immense weight of the system and the public relations problems associated with using it. Don't be too sad, though, a new rocket powered incendiary weapon was ready to go-the M202 FLASH.