Hi
I changed all the kitchen and living room lights (12 x 45Watt) to LED (12 x 4Watt) in December 2013. I just received the electricity bill for February and March (see attached image), the usage is down from 25KW/h to 4KW/h, and the monthly bill went from $285 to $109.
I paid $120 for the LED lights, so they have already paid off for themselves in two months.
I was expecting a reduction in the usage, but not that much. Very nice surprise :-)
Roberto.