I've watched many documentaries and I've appreciated almost all of them. They are usually wake up calls to the public. They inform people, like myself, of harms or dangers we were not aware of. A good documentarian will be that thorn in the side of governments, corporations, or otherwise as they dig and dig to uncover the hidden truth.
Josh Fox wanted to do that here. He wanted to uncover the truth about hydraulic fracturing aka fracking for natural gas. Fracking is a process of drilling and using a high pressure chemical water mixture to release natural gas from where it's deposited in the Earth's crust. The energy companies claim that fracking has no negative impact upon water sources, about a few dozen people that Josh spoke to will say differently. He showed brown water, yellow water, and water that was flammable--yes! Flammable. All of the water came from the wells or drinking sources for regular folks.
The material of "Gasland" was excellent. The narration of the documentary was not. Josh's low, barely audible, monotone voice didn't exactly make one's ears perk up in attention. Perhaps he should've borrowed from the Michael Moore style of lively comedic sarcasm to keep the audience awake. It's clear that Josh was a novice at this documentary thing, so I'll give him a pass.