I got one a couple years back...basically noticed over the years that around February I felt flat and lacked energy. I am convinced it helps lift mood, energy and productivity, even if solely because the room is not bathed in that orangey electric light through the middle of winter.

It is set up on the wall over my PC adjacent to me. It is cheaper to run than normal electric lights and is on over much of the winter months. Not wanting to advertise, but you probably will get a much better deal from Ebay...just check the product specifications (lux output, see above). My only quibble, it's an ugly box. But I would not be without it.