I've used a Lumie Bodyclock Starter 30 as my alarm clock for over 10 years. It's completely transformed my morning. Stick it on a bedside table and its alarm function simulates a sunrise over 30 minutes.
The main benefit I've noticed that it doesn't matter what season it is, the sun always rises at the same time, which makes for a happier circadian rhythm (for me at least).
(I live in the northern U.S where there are long winters and daylight saving is observed, which makes for variable sunrise times over the course of the year)
I don't use the alarm feature though -- my phone is my alarm.