Feedback

I am wondering how people feel about leaving feedbacks.
Personally I think that they are a great tool. A feedback says that you are happy or unhappy with your purchase. It let you tell the seller that you are pleased with their work etc. From a sellers point of view the buyer can be acknowledged as an excellent customer or not. Fast payment is so helpful because the shipping can occur quicker.
I look at everyones feedback history that I sell to. I always feel sad when I ship a runner and never know if the customer was pleased or not. I always wonder if they liked my work.
My friend says that it no big deal. What do you think?
L