It's performance is exceptional and it is simple to use but it's settings and features limited. It has a lot of annoying little problems that should have been solved when the product was designed but it does it's job as a sunrise simulator.
I find it EXTREMELY difficult to wake on time.
I have combined this product with a VERY loud alarm for the days when I really must get up and about three months on that seems to be working. Even without the loud alarm I am managing to rise soon after this one kicks in. By my standards the is really good.
Makes a huge difference to how I wake up, it definitely works. A timer on a bedside light or leaving the curtains open will cost you much less, but if you can afford it I do think the wake-up light is worth the investment.