"I like it" means absolutely nothing by itself. People will tell you they like your idea/demo/whatever all day and have absolutely no intention of ever using it, let alone paying money for it. What you want to hear is "How much does it cost and when can I buy it?" (assuming b2b) or "Can I be a beta tester?" (assuming b2c). Everyone else is fluff. If you're getting nothing but fluff after talking to a bunch of people, your idea is probably also fluff.
"No" by itself also means pretty much nothing. You want to be listening for "No because..." and then evaluate the because part. Is it no because they're not the right audience? Is it no because they don't see the market opportunity like you do? Is it no because they've already heard the same thing from 3 other entrepreneurs and yours is thus a me-too play? Is it no because [fundamental reason you didn't think of and have no answer to]? Etc.
Feedback from people in the target market is hugely valuable, especially if they answer in individual terms. E.g., I will/won't buy because X. But feedback from people not in the target market is rarely useful, especially when it's in theoretical terms. So unless I have some specific expertise, I try to redirect people toward the people they should actually be talking with.
Highly recommend it. It's short (yay!) and very practical and changes the way you think about questioning people.
No affiliation, just like the book
My real issue is how to weed out the legitimate feedback from the bad. No one has ever told me how to identify the difference. It's typically, "yay" means you've done well and "nay" also means you're doing well. When really, either of those responses could be a false positive - but which?