'The consequences for the energy market have been dramatic. US gas prices have fallen by two thirds, the country is now self-sufficient on gas - and the United States enjoyed the largest fall in CO2 emissions of any major country as its power generators switched from coal to gas.'
US prices are probably not sustainable. There's a huge bubble in the industry and its bringing enormous quantities of gas to market and depressing prices below the cost of production. Prices will have to rise otherwise the gas companies will all go broke:
There's a nice article here about how even in the US, where the geology is simpler, better understood and has been drilled for longer than here in the UK, there are big questions about the life and productivity of wells: