How important is customer feedback when building a new feature?

In my case for my latest project, BotMeNot , it's crucial. I'm still in the beta testing phase and I can't keep properly developing without real people coming to test my product and giving me honest feedback. It's hard to find a replacement for genuine feedback because customers don't approach the product the same way as developers do. I think it's impossible (or extremely difficult) to predict all use cases and customer behaviour before actually real people give you feedback.

Extremely important But, one thing Ive learnt is that what people say and what people do can be two very different things. So, its always good to look at the data/ usuage Hope this was useful :) Waq

It is obviously important, but the most innovative products offer something the user didn’t even think they needed. I think the real behaviour of customers gives more information about their needs than concrete feedbacks from them.

@klajko_dora, exactly, "If I had asked people what they wanted, they would have said faster horses" :)))