Supposedly Bhutan consistently ranks as one of the happiest countries in the world. Bhutan seems to have a reputation as a eco-friendly liberal paradise, and pages like this claim that their environmental and spiritual outlook makes them less materialistic and happier than most countries. The Bhutanese government even promotes the idea of Gross National Happiness (GNH) as being, according to Wikipedia, "a commitment to building an economy that would serve Bhutan's culture based on Buddhist spiritual values, instead of western material development gauged by gross domestic product (GDP)."
Is there a factual basis for these claims? I'm personally extremely skeptical since these claims seem to be serving the vested interests of the Bhutanese government while appealing to western new-age spiritual trends. I'm also aware that there are methodological issues with measuring happiness on a quantitative scale. Is there concrete evidence for or against their claims?