Forbes magazine recently wrote an article here about a study that was conducted on whether people that worked remotely were happier. Unfortunately, the study does not say how long the employees were working remotely.
Working remotely has a lot of advantages. There is little to no commute, distractions are (sometimes) much less, and work/life balance can benefit from such an arrangement.
However, there are some disadvantages as well. Humans were built for community, even introverts like myself. As much as I love my quiet office, even I have to stick my head out every once in a while and get some real human interaction. But, working remotely does not have that option. I would guess that the happiest remote workers have found a way to be more social while they work. I know many extroverts that would be gnawing pencils in half if they worked remotely without the possibility of social interactions.