I decided to buy this clock despite very few reviews about it and I must say I am amazed! It worked beautifully on first try! I woke up and felt completely rested and in a great mood. It shows that this product was very well thought-of through research...
The light bulb is a regular incandescent bulb that you can buy in any store and replace easily. They provided a 60W bulb which will illuminate the entire room in a morning-like light but anyone can buy a brighter bulb if they need more than sunrise light. The dome is made of glass and diffuses light evenly so looking directly at it feels like the sun is reflecting on the walls. Actually, I think 60W is perfect because the point is to wake up without feeling your eyes hurt! :)
The clock will also make bird-chirping noises which are produced at random and simulate birds pretty well!
I also tested what happens if the power is cut overnight and I was pleased to see that they have added some kind of internal battery because the clock still worked as expected when the power was back! I even tried cutting power during a wake up cycle and it simply resumed where it would have been according to current time (to ensure you wake up at the time you set!)
Also, a question I had before buying this was: does the light turn on at the set alarm time or before? Well no need to worry: just set the time you want to be awake and the cycles will adjust to gradually wake you up in time!
If you are not awake by the set alarm time, there is a backup alarm you can set that will emit a louder sound.
I highly recommend this product!