I have used several different SAD lights in the past. I find this one to be one of the most effective, the most thoughtfully designed, the most convenient, and the most affordable (for a true SAD light, not an imitator).
Most effective:
As they say, the proof is in the pudding. This light simply works. I have Seasonal Affective Disorder and always get hit very hard with depression starting in early fall through the winter season here in Wisconsin. I used a friend's SunTouch Plus light last winter and it helped a lot, so this winter I got my own. I don't understand exactly how it works, but it definitely does. I also seem to get a positive effect from the ionizer function.
Most thoughtfully designed and most convenient:
This is a very compact unit. Unlike the big, bulky light boxes, I can easily carry it from one place to another in my home. When using my laptop I can easily position the unit on one side for a period of time and then easily move it to the other side so that both eyes get the same amount of light. The angle is just right for use at my computer desk, my dining room table, and on an end table in my living room. The timer is great, and can be set to 15, 30, 45, and 60 minutes and it will turn off by itself. I don't have to be preoccupied looking at a clock or setting a separate timer.
The most affordable:
I have tried less expensive alternatives, but they tend to not be true SAD lights. This one is a true SAD light, not a cheap imitator. It is priced right though -- currently on Amazon it's around $125, which is about half of what other SAD lights and light boxes cost.
I highly recommend this SAD light. I have tried many others and this one is by far my favorite.