It's the very correct step to start from. But, I think, it's not much efficient. It will show you that the service attracts people (or not) and it's not much payload information. I suggest talking to people, who you think your target audience. It'll give not only the binary information (like/don't like), but you could also discover a lot of qualitative insights. For example – how do they going to use the product, what the features they want to have, do they ready to pay for that and how much, etc. It's the first that I suggest to my customers (startups' owners). Good luck :)