I've been using a modified version (50 minutes work, 10 minute break) for about 3 years now. It's invaluable and I don't even use a timer anymore. I don't even stay at my desk for the 10 minutes, I go chat, or step outside, or grab some coffee. I think just the act of getting up, away from the desk does more than being on a short deadline.

I long resisted using the pomodoro technique because, frankly, on the surface it looks a bit stupid. But then one day I tried and found that it is surprisingly effective. I am not sure why, perhaps it provides a sort of marching rhythm to the work time. Anyway, it works.

I have been using the pomodoro method for the past year for school work. (I am in college for engineering) I teach people how to use it regularly. It really does work.